Someone used to make a kit for the B-body to swap the T56 in.
I had one in my 94 9C1 for a while when it was street/strip. It , sadly, got yanked when the car went to full strip and would of got shredded due to HP/Tq of the new motor.
The kit came with a pedal set, the Camaro master/slave, crossmember and maybe a few other parts I can't remember.
The firewall had to be reinforced with some metal. You had to supply the tranny/clutch/shifter and I vaguely recall having to swap to a Camaro T56 ECM.
You could probably put it in a Fleetwood. I don't recall anyone having one during the heyday when these cars were popular. I think there was someone with a Roadmaster T56 swap though.
http://carphotos.cardomain.com/ride_...0003_large.jpg