Hi Christopher J here. Re the internal muffler on the drum in question. I have a 1966 supra and a 1967 Acro and they both have internal mufflers as stock. I don't know of any that do not, but then it might depend on the market, and age. Anyway good luck with the heads and why not the
ludwig heads? The heads are usually chosen when the drum is designed, not that you couldn't improve or change the sound to be more to your personal liking. Let us know what you choose.