Try looking it up under dow corning products, I think called graphoil- generally used in high temperature valve packing seals, which are very similar to the rear main seal in a 216 engine. If Dow corning does not have it, Look for your local swagelok dealer and tell them you need to get some graphoil lubricant, they will have to do a tech service request to the factory to get it, and it will take an extra week, but they can get their hands on it. www.swagelok.com

They might be able to get it in little one time use tubes where you tear off the end.
It is good stuff

If that does not work, my local refinery(That I work with) used pure nickel special for gasket dressing, pure nickel special is the product name. It is an anti seize
I have personally used Loctite nickel anti seize in the same manner with success, I use it to dress head gaskets, exhaust gaskets, as well as the bolts and such-

I kind of ramble a lot, but I hope this helps



1949 Chevy 4400 Big Red
1949 Chevy 3600 Bob's Truck
1949 Chevy 3100 The Investment
1949 Chevy 3800 the Won Ton