DYNOTECH FTW!!!
http://www.dynotechperformance.com/
Eric and Jim are great to deal with. I had a 79 TA that was spitting out trannys until Eric did a TH400 for me. And they spearheaded the masterwork of installing a 200R4 in my 73 AMX.
ASFAIK they will work on just about anything...first time I went to their shop they were doing a tranny for an Escort, so I'd say it's safe to say they will do whatever it takes to pay the bills. But keep in mind there are usually no less that 8-10 Grand Nationals there awaiting their attention.
If anybody goes there, just drop my name. I'm one of their favorite cartoon characters. lol