I have a 74 440 that I am going to put into my 67 belvedere. My question is that I have a set of 69 906 heads off a Polara cop car I know the valve seats aren't hardened but I talked with a local Engine Builder and he said unless I plan on driving it every day it probably won't matter much. My question is if these heads will make that big of a difference compared to the stock heads on the 440 now.Thanks,
Tony

 

what are your intentions for the car?
my 71' had 346's on it i believe, low compression low flow smog heads.
guessing you have the same on the 74 block.
cant go wrong with the trusty 906's if your not going to go aluminum.
they can be ported to flow pretty nicely.

 

They are good heads. Are you keeping the same pistons? You will need to check what your compression turns out to be.

 

Thats a good question for Polaradude! He is the cylinder head GURU!

 

Tony, the heads won't really matter much with the low compression of the '74 block.

john

 

Here is my two cents: Rebuild the 906's - shave them to what is within spec and put them on. When using a head gasket, you can select a thinner metal version. Between the better air flow and shaving, you will get a bit of better compression. Your 346's are a good head as well, both are open chamber with the same valve size. rebuild and shaving is about 500 +/- some. so take that into consideration.