FWIW, Larry, the owner of PT.com has a Richmond in his car and says it's getting swapped out SOON!
I have driven cars with T56's and liked them a lot! I have a T56 for my car and got it for $1100 and it's a fresh rebuild out of a '97 Camaro.
There ya go....in my mind, I have a far better trans for less money and wouldn't even consider buying the Richmond.
Remember, just because you hired a builder doesn't mean they get to choose the parts....this is your car/build and you make all final decisions...otherwise this isn't going to end well! Job one is to know what you are building and understand it....you are talking a lot of money here, especially when you are paying for labor! Don't get in a hurry...you have time to learn....we all had too!!