I asked the seller what the bore size was and after some going around he responded 3.510 which I kinda doubt, but it would be nice if it were true.

Up to what compression ratio are the these gaskets good for? Also does using such a gasket require milling the head and the block for 100% flat surfaces?

https://www.ebay.com/itm/127009571102

Good flat surface on both sides, block and head certainly helps.
Head studs will certainly extend the compression ratio level.
Many people forget that steel shim gaskets require at least one retorque after initial break in.

Only solution that I know for HIGH compression ratios, over 12:1, would be studs, copper shim and oring block.

I agree with you, 3.5 seems like a big bore for an older steel shim.

_________________
Hyper_pak

Ryan, has the Multi layer steel Head gaskets that he made up and he has run at over 13.0:1 without any troubles. They are not cheap though.

If you find the Ozzie big bore gasket, we have run that at 13:1 also. But they quit producing those.

_________________
2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6

I have used the stock steel shim gaskets on 10.5:1 Engines with no issues.

I also reused one recently on a 9.5:1 Build.


Greg

_________________
http://www.youtube.com/hyperpack