Does someone make a shim head gasket for a 400 SB that includes the appropriate steam holes? I have thumbed through Summit and Jegs and can't seem to find a shim gasket. The closest I can find is a copper head gasket. Manufacturer and part number would be greatly appreciated !!

The origional GM 400 SB head gasket was a shim gasket.

If its still available, you should be able to buy a new set of origional shim style head gaskets from any GM dealer.
You would have to order it for the origional application that a 400 small block motor came in.

Like a 1970,71,72 Chevy Impala 400. The 400 SB was refered to as a 400 2bbl motor back then as the 402 Big block was refered to as a 400 4bbl. You could get either motor in those cars back then.

I had one of these cars a long time ago. Tire baker....

Another possible source is Year One restoration parts.

Great! Thanks for the information. Do you happen to remember the thickness?

.015"