I think if you get the auto double hump it will work with minimal if any mods
I don't know it the AOD4 double hump and the t-5 double hump are the same mounts. Wrecker would be a good place to look or 5.0resto.com.
My car had a C4 in it when i got it...it's a factory 5 speed car....the catch is that '85s didn't have true duel exhaust, so it's anyone's guess as to what year the cross member came out of...BUT i did use the same cross member for my Tremec. The only modification you have to do is cut the spot welds on the "tubes" at the ends of the CM, and they'll allow the CM to slide forward and backward and you can then figure out where you need the mounting holes for the trany to be, mark that spot and weld it back. You DO want to weld it back (don't ask me how i learned that one..lol).