The price for the Tremec TKX is currently showing to be $2795. The American Powertrain bellhousing for Tremec to Mopar is listed on Summit Racing listed at around $450. SST sells what they call their lighting edition shifter with over 25 shifter positions. I think the total would come out significantly less than the $6K you would spend for the other transmission that you may or may not get for a very long time. Then there is the question of parts to fix said transmission in the future if something goes wrong or a simple rebuild is necessary.
So if you don't have the space, ability to fabricate the mounting, what is that going to cost? To quote the original cheerleader for the TKX in another thread:
"I called and inquired about what it would take to put my TKO Perfect fit kit into a different car, specifically a big block, and was told that they were specifically fitted to a certain model. I couldn't put the kit in say, an A-body or B-body, but if I wanted to put it in another E-body with a big block the only thing I would need would be a bellhousing." Lots of folks have A and B-bodies...