[BlenderWizard]

Originally Posted by bobo383

What he said. Compression would be lower but you'd never be able to tell it in an otherwise stock motor. Look to see if the 5.7 heads have very tall, very skinny, evenly spaced intake ports (like a 5.3). If so they'll probably work. Older intakes and heads had siamesed rectangular-shaped ports (not eveny spaced, the ports were paired up), like my 64 Impala's 283. These would physically bolt onto your block but would not bolt up to the intake or exhaust manifolds.

I'm not sure a Gen I or Gen II head would even go as far as bolting onto a Gen III block.

I think you'd have a better chance of getting a Ford head to work.