Here are Cody’s pictures of the caps. (They look nice!)

Chuck, CGT-C5834-023 and -040 I’ve tried advertised at 4.165 and weren’t round bore and measured kinda egg shaped in the 4.200-4.320 size range. I have some old Victor 3389 gaskets here that measure .038 thick and 4.300 bore or a 3417 Victor that measures 4.165 intake to exhaust direction and 4.220 water pump to flywheel direction, but they measure .048 thick. I really like the 3389 gasket for anything 428 bore and smaller. The last felpro race gaskets I measured were over or at .050 thick and 4.400ish bore. As always I never assume anything anymore and always measure everything at least twice. Good luck!

Hey Kevin, if you want to post some pictures of this project that would be great, I can’t seem to find your email address or how to get to it on here.

That is the former Phil Glass car. David Garton found the car and mechanically restored it. It is OG paint and Blair Patrick built the engine. No maybe to the story its real deal!

I can confirm that, I was a small part of it when the car came up years back.  David researched, bought and got it back to it's glory.  Very cool ride, and nothing he owns is junk, lots of cool toys.

In an engine like the 462 above, changing a Felpro 1020 to a 4.20 bore only gains .084:1 compression, 10.315 to 10.399.  Not sure I'd bother for the money.

However to answer the question, I have only done a couple at 4.375 and used a 4.40 Cometic and worked well.  So I would not be afraid of a 4.160 engine, assuming a properly prepped flat surface and a Cometic with a 4.190 or larger bore. 

Test fit if going close though, because every so often you get a weird one from Cometic, not common and I use them all the time, but have seen a couple that the bore was not centered