motor swap

i just bought a 1970 pontiac catalina 400 engine(30k miles)for 100 bucks,and im seriously thinking of stuffing it into my 82' trans am,wich currently has a fresh 70' chevelle 350,thats comp cammed,flat pistons,and big valve heads.I work at a shop so the 30k miles on the 400 im okay with.The 400 I helped build,it has flat pistons and a mild cam.

i just want to get some opinions on wich is faster and better.A flowed out pontiac 400,or a flowed out SBC 350?I have available a set of 70' gto judge heads i can get for 300 bucks,are those any better than the heads on the 70'catalina?Im not very schooled on pontiacs,as per expert parts identification.Im pretty sure instead of selling those judge heads to a customer,i should just put this 400 pontiac engine and trans in my firebird,and talk my boss out of those judge heads.If i do all that what are the chances of a 350SBC ever passing me?

Judge heads? Need a casting number. Tons of myth and superstition here...
It's a debate about the Pontiac versus the Chevy. The Chevy will drop right in and be plenty powerful. For each dollar spent, until you get near the $5K line, the Chevy will give you more for the money. If you're wanting the most regardless of price, the Chevy will also be a bit better. But in the 500-600 horsepower range, the Pontiac will deliver better street performance and live longer.
Putting the Pontiac in the 3rd gen F-body is doable, but not straightforward. Indian Adventures (Foxboro, Mass) sells the mounts and headers. I've seen MANY, running a 400 on pump (93) gas, go deep into the 11s without adders, and in true street trim. The Pontiac makses more torque at street speeds. Horsepower sells engines, but torque moves cars!

If you have lots of money and time then drop the pontiac 400 in. It will be way more fun. If not, I would stay with the Chevy. Parts are cheaper...Good luck!

well ive just been lookin at a few facts and doing some comparing,and it seems to me a pontiac 400 puts out the same torque stock,as a mildly modded out 350.So if i was to go to performance heads and cam and intake on the 400,i wouldnt even miss my SBC.
But then i investigated it even further,and compared the 400SBC to a 400 PO,and mayhaps a 400SBC has more potential.
Ive watched a lot of nice motors get destroyed due to over-reving.265-330 SBC's can be spun up to higher rpm's(9000 or so) and survive the abuse for awhile.But your 350-400 class SBC's cant take the abuse and go into meltdown or whatever you want to call it,if you run it up past 7,500 rpm's all the time.
My question in all this,wich can take the abuse of high rpm applications better.I think its the SBC.

The reason im wondering is if im going to cam it up at all (the 400PO),i will cam it where all the low end torque is trimmed off the bottom of the rpm curve,and placed it all at the top of the RPM band.My car isnt a full framer see,and i have to pick a cam out thats like a 3000-7000 rpm range cam,or i will prolly twist up my car body,with the crazy amount of low end torque of a factory 400PO cam.

You're right about the RPM potential of the Chevy vs. the Poncho, if all things remain "stock". With proper modifications, the 400P is a good runner. The 400SB has a much weaker block casting than the 350, so a 383 is the best of both worlds.
One of the biggest differences (aside from the torque output) is the weight. The small block is about 140 lbs. lighter than the Pontiac. In certain cars, this is meaningless. In other cars, it's quite important. The nose weight of a car intended for handling and all around performance is something to consider. The T/As and GTOs with the Poncho are definitely good handlers, but the suspensions and weight distribution are designed with the heavier engine in mind. Altering that balance can hurt, no matter which way you go.
If this mainly a street-performance car, the Pontiac is something to be considered. The low-speed power and efficiency are both good things. if you decide to build a Poncho, do NOT approach it with the same mindset you would use to make a 350 Chevy perform. You'll end up with a pig of an engine, that won't live. These engines respond well, but to an entirely different set of changes than the Chevy. And rear gearing is another important aspect of the differences between the two engines. The Chevy likes to rev, and likes stiffer (higher, numerically) gears. The Pontiac likes to "spread" the torque out a bit, so taller (lower, numerically) gears are called for in the same application.

the heads on the 400 right now are 7j2.The engine is rated at 200HP.whats with that.Big cubes,sad output.I want to run the pontiac engine but it looks like i will be sacrificing too much power.I may as well find a 70's grand prix or somthing to put the 400 in,and maybe go ahead and keep my 350 chevy in The t/a.I know it has to be makin more than 200hp please i cant just go around makin my car weaker

Don't pay much attention to the ratings from the '70s. None of it has anything to do with what we're getting out engines today. That weakling 200 horse 400 will easily make 400 horsepower with those heads. A head change can make it to 500 with little else. A good valve train is mandetory.
Of course, you can build a 350 Chevy to make good power, too. But for comparison's sake, look at the output numbers for the 350 of the same year/application as the 400. You'll find the Pontiac is more than competitive.

yeah i was looking at that.After i started looking in the chiltons and seen sad numbers next to the SD455's,i knew somthing was wrong.I think they had a stingy dyno.My heads have been surfaced twice and each time twenty thousanths was milled off.Im not sure what exactly what that does for the compresion,but my 400 was rated at a whoping 8:1 compression.Now that 40 thousanths is gone i figure it for maybe a 9:1 or better.I have two different figures or what size valves the 7j2 heads have.One chart says they are 196 heads.and the other says its 2.11/1.77's.Im guessing it is in fact a 196 head,if it was rated at a pathetic 200HP.I have a couple of sets of 6x heads to chose from,but from what i understand is more to it than that.They made multiple types of 6x heads.some are over 100cc's,some are under 90 cc's.

According to the previous owner the block i have is bored out 030 or 040.I would have liked to put a set of flat tops in it but if its aleady bored 040,i can already hear mike my machinist.