Unless it's going into a '70 model car, in which you want a correct numbers RA3 engine, I see no reason to use the #12 heads.

I personally would sell the RA3 parts to somebody who must have 'em for their RA3 resto.

But, if you wanna use the block & heads, AND get 400hp. I'd buy a dish piston stroker assembly from Butler. Easy pump gas 400hp/500 torque, with a mild cam.

If you wanna use the block, but not the heads, I'd go with a flat top stroker assembly & 6x-8 heads.

If you wanna use all the parts you have, I suppose you could have the chambers enlarged, to reduce CR. Then use a cam with lots of adv duration, like maybe a Summit 2802, or even an 041 clone, with Rhoads lifters.

Obviously, the 3.75 stroke engine will have less low end torque. So, it all depends on exactly what you want from it.


"...1970 400 ram air lll...the original ram air cam..."

The original cam would be an 068. A lowered compression 400 won't make near 400hp, with an 068, IMO.