I found some Vortec Heads 10239906
The guy said and I quote
"The combustion chamber is 64cc from the factory. The shop that built these heads milled them down to 52 cc to increase the compression and horse power."

Is that a good thing ?
and do you think the heads are worth 400obo$

If I got them would I have to change anything on my motor other than the intake?

Thanks,

 

Actually, while GM claims 64, they're usually closer to 61cc. But 52cc is fine for a 305, on a 350 you'll need some Keith Black 22cc-dished pistons to run pump gas. And at that point, you'd be money ahead to buy some other heads instead.

 

Nothing else will need to be changed. Accessory brackets will bolt up fine as well.

 

For 52cc chambers you're gonna need some massively dished pistons to be able to run pump gas. You also need a different intake manifold.

 

If you do run them, you'll need to have the intake manifold machined because of how far the heads were milled.

 

This is something that doesn't get enough attention. Decking the block or milling the heads means the intake needs a trim too.