If it is pretty much rust free, and you don't mind a LOT of "waste your time" PM's... parting it out might make you a buck or two.
is a site that deals with ONLY full size Jeeps and a lot of people are looking for parts in good condition.
The TF727 is a stout tranny, what you can easily replace it with mostly depends on which transfer case it is setup with. The AMC 360 engine in it can put out a lot of low end torque, but be prepared to spend some $$$$'s building it beyond stock.
TH400 might be the solution to your tranny issue, but like stated above it depends on your transfer case. TH400/D20 combos (especially with a twinstick conversion) are going to be an excellent combo off road.
A little more money to get an operable rig shouldn't be a problem with your mother and brother, you never know just talk to them about the situation and the possibilities.