first of what is the differnce between these two they are basiclly the same price but the chamber size is the only thing different so what does that do? and i have read that the 65cc chamber would be better suited for the 350 tpi is that true or will the 75cc run any better?

you will loose to much compression with a 75cc head on a stock L98, go with the 65cc, personaly if its with a LTR TPI still on-top i'd use the AFR 180's and not the 195's in 65cc form

Only way I'd run the 75cc heads on your car is if I was adding boost

thanks for clearing that up and what do you mean by ltr tpi on top??

LTR = Long tube Runner

your stock TPI is a LTR format

I am using AFR 195's, w/ 62cc chambers, on a stock short-block with a LTR TPI set-up...the car has excellent drivability. In fact, I'm swapping to HSR to kill some low-end .....and boost the top-end

Bill

if i could change i would go with the afr 65cc because i lost alot of power using the 75cc its a dog down low,but i may change to a procharger d1.

how much Compession are we talkin about losin goin from a 9.6-1c motor with stock cast iron heads to the 75cc or 65cc....what if you had them milled to 58cc?

I think you would have to angle mill them to get down to 58cc. I believe 60cc is about it for a flat mill.

The combustion chamber is just to set your compression, yes, a 350 will want 65 with flat top or dish pistons, 10 ccs is roughly 1 point of compression, remember also that your head gasket is also a plays a large role in compression, if you have a block that has not been decked you fo not wany a fel-pro .039 head gasket. For iron heads you can use a steel shim, but for aluminum, Victor-reinz makes a gasket that is .025 thick and will not brinell aluminum heads, if you used this gasket you would have decent compression, and a good quench area, which is also good for power, with better quench you can run more compression on pump gas, it is the best of both worlds.
I believe most 350s have 76 cc heads, so you are going to gain about a point of compression with 65s, which is what you want, for a performance motor with aluminum heads, you should get as close to 10:1 as possible.

i guess the reason i ask is because i may have found some TPIs AFR heads but there 54ccs. Ive been told my motor is 9.6-1 now with the stock cast iron heads....would 54cc make my comp to high for the streets? I always run 91+oct gas so that makes no diff to me.

Yes, I would imagine a 54cc chamber would give you 10.5 to 1 compression with flat top pistons, which many people consider to much compression for pump gas, there are many other variables to pump gas operation, like quench, cam size, combustion chamber design, etc., but I would try to stay on the safe side with about 10 to 1 compression, The 54s Are probably for dish pistons or 305s.Are you sure you have 9.6:1 now? that sounds awful high for this era of motor, you may need to look into that before purchasing heads.