Can you use 454 heads on a 350 small block?

Yes, you can use 454 heads on a 350 small block, but you will need to use a different intake manifold and possibly some other modifications to make them work. The 454 heads have a larger combustion chamber than the 350 heads, so you will need to use a thicker intake manifold gasket to make up for the difference. You may also need to modify the exhaust manifolds or headers to fit the larger ports on the 454 heads.