'67 GT-500 heads - need advice

The short answer is ,yes you should use another set of heads. On a less historic and less valuable car you could cobble it together and try and mill the intake manifold to fit but it just doesn't make sense to do it on a GT500 IMHO.Bob

 

Usually the machine shop would tell you; "we milled them XX.XX" and let you decide what would be next. Like correct the intake with milling also.
But like Bob said, historic accuracy might suffer.

 

IMO this is the exact opposite of what you should be seeing. Milling the head surface (combustion chamber side) should drop the intake mounting holes lower and the intake should be too wide.

It sounds like you have the opposite problem - the intake is too narrow.

 

The heads will be further apart than closer when milled. We run into this all the time. I agree with Bob and Rod about the historical accuracy however while I would replace the heads on a 67, I would mill the intake on a 68 500. The 68s have the VIN stamped on the heads and to change them I believe would be more damaging to the authenticity of the car. Honestly the amount the intake gets milled is undetectable anyway.

 

The VIN stamp if on the heads would certainly make milling the intake a more compelling option. In a lot of instances like I believe it is in this case, I don't think it was a numbers matching engine to begin with. If the VIN stamped head is not a issue the down side on milling the intake is that one can usually tell that the intake has been milled by looking at the gap or distance between the front of intake and the engine block in the front (no visual on the back). The opening is too thin for a normal cork gasket (most use silicone there). The thin space is dramatically different from the normal wider space . If you doctor the opening with smeared silicone so as to disguise the milled intake(seen that done) you haven't gained anything but just transferred the problem to a workmanship issue. I agree As Tim said it is hard to detect a milled intake unless you know where to look and even then it might go unnoticed if one were preoccupied with other issues when examining. Again this is mostly relevant to a historical significant/valuable car where it isn't prudent to compromise in certain areas. IMHO I would much rather replace the heads "IF" the VIN question isn't a issue. Bob