Re: ZZ4 heads on a 327?
According to my old Chevy Power catalog, the ZZ4 used "12556463 Aluminum Cylinder heads, 58cc combustion chambers" 1.94 intake, 1.50 exhaust with 0.100" raised exhaust runners and D-shaped exhaust ports. Center-bolt valve covers.
Depending on your pistons, the 58cc chambers might be an issue. Could end up with crazy compression ratio or physical interference between the piston dome and the cyl head.
Also, I think these use the 87+ intake manifold bolt angle (not sure) so you may need a new intake. You'll definitely need new valve covers (center bolt)
With the raised D-shaped exh. ports, your headers will probably bolt up, but you MAY have issues with the headers obstructing part of the exh port.
Yeah, I know. That's a lot of maybes. Fundamentally, they'll fit the 327, just need to be mindful of all the details.