Re: alto jazz mouthpieces
The C* is the tip opening size. There are a variety of Selmer mouthpieces with a C* facing, but most of them are designed more for legit playing. For jazz, rock, funk, and blues, you're going to need something with a more open tip for better projection and volume, and better tone. Metal pieces are more popular for tenor than alto. Here are a few suggestions based on price.
Rico Royal Graftonite B5 or C5. Both have a fairly open facing. The C5 has a larger chamber and is better suited for jazz. These pieces sell for around $20. They're very good for the money.
Otto Link Tone Edge 6* hard rubber. This is one of the best mouthpieces I have ever used on alto. They sound fantastic! They're a great piece for a vintage sax like a Conn, King, or Buescher too, because they have a large open chamber.
Meyer 5M. The Meyer is very similar to the Otto Link. They also have a fairly large chamber. They have a slightly different feel.
There are many great hard rubber pieces for less than $100. These are my 2 favorites. I really haven't tried too many others.
The quality of the Jody Jazz pieces are very good. I use an ESP metal on tenor, and it has a very powerful sound. Of course, playing a 1948 Conn 10M has a lot to do with that too, but this piece really works well with the 10M. I want to try a Jody hard rubber piece on my alto soon. They're definately worth looking into. The Peter Ponzol mouthpieces are also very good quality