Re: Quick question
It's possible to lap the joint in by careful use of grinding paste between the barrel and cases, so allowing you to use a gasket paste, but you'd have to be sure no grit went inside the engine for a start and clean it all off after doing the job. Then there is also the question of altering transfer port timing because the barrel will sit a small but measurable bit lower than it did.
You don't have to have the part from your supplier though. There is a gasket material supplier in most towns that will sell an appropriate sheet you can cut to fit.