Back in the day, we would call these "o-rings" and use .015 stainless wire. Grooving was cut with a boring bar or a facing tool with a shop-made radiused groove cutter, and only the block was done because a deck job was cheap and many builds could survive a .015 decking compared to decking the heads. Nobody cut two o-rings and opposed (mated) them on the block and heads. So with these diesels, the minimum wire is .049 and it is run on both sides of the gasket. That's quite a bit different than the nitrous and blower motors of the 80s and 90s. What's changed to require two fat o-rings?