was wondering if I would be able to bolt on heads from a 400 or 455 to my 350. They are stamped D.

 

Hello
I tried to reply to your email and wasn't able to. I have lots of 350 heads or if your close enough complete 350 motors with 1968-72 castings. If your interested in a set please PM me with your zip code and I'll get some costs including shipping for you.

Now to address this post. Big block heads can be used on a small block but the work to make it happen isn't easy. Also, is the letter D cast into the heads just to the left of the #1 spark plug hole? If these are indeed letter D heads they are scarce heads used on 1968 and 69 W30 cars and Hurst Olds engines. Please verify what your looking at on the heads or if you have them post a picture. John

 

Yes they will bolt up, but why? Combustion chambers are large (lowering compression) and ports don't match SBO intakes without porting. Unless this motor will be running at high RPMs frequently, this is a waste of time and money. The W-31 motors simply used big block valves in otherwise stock small block heads. And as noted, if they really are "D" heads, they are worth well into four figures.