Ohhhhh goodie
Engine-
I totally support the vortec/TPI combo, im doing it myself but with a 302cid sbc and an accel superram intake. If you are going through the trouble of pulling the heads and intake, i might suggest you also go far enough to pull the pistons and put in a set of good forged flat tops and gapless rings. a good port and polish job, modifications for higher lift cams. manley street flo valves, and comp cams beehive springs. The intake baseplate for the vortecs flows much better than the stock unit, so you should also add a set of higher flow runners and a larger throttle body. say the 52mm units (i think thats right) an adjustable fuel pressure regulator, higher power capasitive discharge ignition system. for a cam i would look at a strong Xtreme energy cam from Comp Cams, computer compatible of course. hydrolic roller and all that. somewhere along the lines of an XR260 cam. The headers are a great choise, i put a set of edelbrock TES headers on and they were definatly a strong performance increase, i just cant change my spark plugs. followed up with a good cat and exhaust, and youd be making some good power. say around 350-400 and some major torque.
keep in mind that with these extencive mods you are going to have to have the PROM reprogrammed to have the car run to its true potential, even with the highly adaptive MAF system.
Tranny
you should have the TH700R4 in that thing, here is what i did to mine and was floored in the difference in performance, probly the best performance related investment yet. I threw out the stock stall converter for a 2600rpm stall unit with a kevlar lockup clutch. then had the guts replaced with a B&M trans kit and stage two shift kit, then i tossed the weak camaro 1st to 2nd shift servo with a high pressure corvette unit. This provided the strongest seat of the pants change in performance, it shifted so hard coming off the line the first time i took it out, i accidentally pulled it from drive into first gear on the 1st to 2nd shift.
Driveshaft
get an aluminum unit out of a fourth gen, you might have to swap the yokes, but thats not hard.
Rear end.
You didnt say if you had the ten or nine bolt rear unit, so concidering the rarity of the nine bolt, ill talk about the ten bolt unit.
The ten bolt has a bad rep for being a weak in the knees rear end but it can safley handle 400-450hp if proporly put together. I would suggest ditching whatever rear end you have, as well as your axles which are both 26 spline units, and replacing them with the 28 spline units from a 89 and up camaro or firebird. You have a miriad of choices regarding what to put in the rear which is kinda limited by your budget. Personally for what youre looking to put together a good eaton or auburn posi would be good, and even a torsen rear from a fourth gen Fbody would work well up to around 400hp. If money isnt really that much of an issue, a detroit truetrac is basicly a performance torsen that will not be prone to the problems of the factory unit that tends to have breaks in the carrier around 450hp. Up the ratio from the stock one to a 3.73 or 4.10 something like that. If you plan on doing alot of highway driving id keep it no lower (higher numerically) than the 3.73. Make sure the settings are within spec and the rear is spaced and gapped proporly to avoid wear related damage, and finish it all off with a rear diff girdle cover that will have two screw down buttons to hold the carrier caps in place under high power acceleration.
Suspension
Camaros have a great rear end setup, decent front end setup, and a weak frame setup. For any performance application subframe connectors will be a must. there are many other parts that should be concidered, to get a pretty complete list, look up the total system offered by Hotchkiss performance. Its a single 1300 dollar kit that has just about every suspension upgrade available for the car in question.
These suggestions are quazi budget baised around a simple street/strip car running pump gas and naturally asperated. obviously there are also more extream things you can do involving forced induction, engine swaps, (383 - 454 cid sbc), and all that so if you are planning something more major then feel free to ask for somehting along those lines, i pretty much just covered the basic points.