requesting real life experience with 904 lock-up with manual switch

I like the brake release suggestion. I'm installing an aftermarket speed control that needs a release using the brake light circuit anyway, so using the same added circuit should be a breeze. I got what I was really concerned about - whether using a switch would somehow bollix up the overall transmission function or compromise its longevity and what I am hearing is that it's just not a problem.

I am looking at sourcing the transmission and converter from a Portland, OR based rebuilder. Does anybody have a source that they would recommend instead? It doesn't seem that any of the usual sources for non-lock-up transmissions (TCI, Performance Automatic, etc.) offer a heavy duty (or any) version of this transmission.