Georg,
I agree, they are simple transmissions, but they are pretty much bulletproof, you can spend almost as much on a Powerglide that will handle close to the same HP but you would be rebuilding it every 10-15 passes.

A better source you might look at is:

http://www.insidetopalcohol.com/forumdisplay.php?13-NRE-X-1-Heads-Free-Classifieds

Got your PM, going to be out most of the day today, but when you get a chance give me more info about your car and what type of usage you intend to do with it. I'll try to help any way I can.