I am rebuilding a 93 460 and the heads are flat wore out. They have been redone a few times already and they are just finished(bad guides and seats).

Can i run say a set of 80s carbed heads on this FI motor. Is there a difference?

 

No you can't.
The port locations on both the intake and exhaust sides are not going to match.

 

You can have the guides and seats machined out, and new press-in guides and seats installed. Seats are hardened steel, and will last longer; guides will be gentler on the valve stems, I believe the press-in guides are bronze-silicon. Fixes the heads right up, no problems.

 

That is true but I got the magnaflux report back. not good

 

Cracks between the plug hole and the exhaust valve?

Sorry to hear...