Yeah, if you're selling the car anyway, just do it as cheaply as possible. One thing is for sure, personally: If my trans ever goes, it'* getting an INTENSE tranny for sure.

I have a GTP tranny in my Bonnie, the side cover fits fine (even with the bolts screwed into it), but I did make new tranny cooler lines for mine, since I ran a seperate tranny cooler instead of using the radiator.

Exactly what'* being done with mine.
I swapped the Bonneville side cover because the GTP side cover had a hole in it.