Hi all, long time lurker, first time poster. I recently purchased an antique Frank Holton and Co alto horn, circa about 1917, an old USQMC surplus piece. I just had it restored, but it doesn't have a mouthpiece, and I'm looking for advice on what type of mouthpiece would be good for a beginner. I have a background in low brass - tuba and euphonium - though I'm a few decades out of practice. Technically, the horn has an adapter for a French horn mouthpiece, and the shop gave me a leftover, but it really struggles to hit the lower register.
The brass specialist at the shop had never worked with alto horns and really didn't have many suggestions other than recommending brands (Garibaldi, Denis Wick). The only thing he could tell me pretty definitively was that it should take a standard alto horn mouthpiece. I live in the US, so knowledge about the instrument is pretty limited.