307 for my 1978 van?

[rickpilgrim1]

With gas at $3.59/gal and a DOA 350 in my 1978 G-20 conversion van I'm re-thinking the 400sb thing and thinking the 1973 307 I have may be the wiser way to go. I have a set of the L69 305 heads w/mild porting done,(my sons gen 3 Camaro headache), a set of aftermarket hyd roller lifters(Howard), the 383HT GM cam, a performer intake and EDL-1404 500cfm carb. Also have a set of 1973-1987 truck headers and the van has 2 1/2 dual exhaust allready. Also have the complete ignition system,including all the sensors for that L69 305, if not that the DOA 350 has an Accel HEI that works in any sb/bb standard deck engine plus all the chrome odds and ends.
The van has a TH-350 trans with a doug nash od unit that works great, and is 3.54 rear axle. Also tips the scales just shy of 5K, at 4957 lbs and that's with a 1/4 tank of fuel(aftermarket 50gal tank) and 1 person.
The 350 that was has a hole in the block from #2 rod, but at 194K mi thats ok, I have a good 1972 400 sb and the 73 307 that was rebuilt 487 mi before the truck was totalled. All the people tell me to junk the 307 and go 400 as the van is heavy and fuel mpg of 16 is good allready and the 307 will be worse than the mostly stock 350 in power and mpg. We all know gas is only going to get worse so ..........
Never had or drove a 307 chevy powered anything in my life so if anyone has any thoughts or opinions I'd appreciate it.

[silicon212]

I agree the 307 will most likely be underpowered and will thus use more fuel than the 350. The 400 won't be better than the 350 for reasons of economy, but it will have some killer torque.

[rickpilgrim1]

I was thinking that way at first also, but chevy did put 305 TBI motors in the newer vans, not to mention this won't be a stock 307 2bbl anymore, it will be more like the 235hp marine 307. With the OD unit I can change the 3.54 to 3.73 easily without a great milage penalty... As to the 400, we have a long rod, port reworked, recammed and offy intake eqipped 400 in our 93 3500 4x4 dually and while it is better for all around power than the 6.5 diesel the fuel useage is only about 11mpg and thats with a 4l80E od trans and 4.11 gears. Not to mention the van does not have room for the big radiator the truck has to keep it cool.