700r4 to TH400 two questions

[bryantreams]

Ok so I think my second gear band has completely gave up in my 700r4 and I was already wanting to go with a turbo 400 with full manual valve body. Rather than buy a used transmission in unknown condition I think I'm going to go with a new unit. I plan on swapping to a turbo 5.3 later this year and I need something to hold up to about 600 hp at the crank. The truck will see 99.9% street duty but may take it to the track once or twice (I'm not concerned with et's). So, onto the questions.

1. I think I have it narrowed down to a Rossler Terminator 1 after initially considering a TCI, B&M, or Hughes you can get from the popular mail order parts guys. Does anyone have a suggestion for a different route with a budget of $1500-1700 for the transmission?

2. I've tried searching and can't find any information on what I'll need to do for a crossmember. Can mine be modified to work with the th400 or should I fab a new one anyway since a lower ride height and dual exhaust is already an issue?