Re: New alto mouthpiece!! HELP
Beechler (hard rubber) diamond inlay 6S6
Vandoren Jumbo Java 55
Dukoff D6 silverite
(But the Dukoff silverite pieces are made very inconsistently and could require refacing to play properly)
If you're used to hard rubber, I recommend sticking with hard rubber. The fit of the mouthpiece to your embouchre will be more familiar than with metal mouthpieces which, for the most part, are smaller and require a somewhat different embouchre.
One mouthpiece I am really happy with is the Selmer Metal Jazz on alto (they're not for me on tenor, though). I have a C* facing which has a nice brightness to it without being harsh - easy to play but projects far more than the same facing on an S80, for example. It's more closed than the ones I listed above, so it's a good halfway point between a legit mouthpiece and a screaming Jumbo Java. The good thing about these is that you could use the same reeds you're currently using on your Morgan to good avail. SMJ doesn't take you into Sanborn territory, though.