Well here is what I can elaborate on here.....The length of the transmission will tell if you will come into contact with the torsion bar cross member (you will have to determine how much fabrication you are willing to do at this point) The shifter on the E-Bodies is offset in manual cars, which creates an adaptive issue to the internal rail shifted transmissions. I have sold Tremec' (B-Bodies transmissions) to folks that did not want to install the required 4 speed transmission "hump" and have the shifter in the middle of the transmission tunnel. You may have to fabricate a new cross member - which is not a big deal. If you need pieces (blanks) for a general template - I can waterjet cut some for you (cost is about $50.00) that you can fabricate your own mount from. Note that you will have to cut / grind / weld to acheive the correct driveline angle.
You can do this, it takes time and money for sure. If you are mechanically inclined and can fabricate go for it. One item to really consider is the future of your car. The transmission is always the unassumed part of the build for any build. Consider your future plans and research the torque capacities of the unit. Different years may vary since technology and material science has come into play. Sorry for the rambling on here.....
Feel free to ask questions, I'll give you an honest opinion and point you to the suppliers that I use for the Mopar kits the we sell. This is not rocket science, it's just some good old applied math and the sourcing of the right parts to work together as a package.
Tony Edler
Classic Mopar 5 Speed