On a 76, you have a passenger drop on your front 44. The only problem with using any case mated with a TF727 is that they are all driver side drop fronts. You would have to get a new front axle. If you were to get a new axle, I would suggest a NP208 t-case over a 219. [IMO] Also with these cases, the rear output if for a centered differental. You should have a passenger offset rear 44. If you were to put one of the newer cases, it would make rear upgrades a little easier, being that it is a bitch to find rear offset axles.
Now, the quadratrac case really isn't all that bad, regular maintance and care of the case [esp. the vaccum lines], should yeild you good results. I dont know if you have a low range quadratrac unit, but the low is decent- 2.67:1 if I recall.
So in the end, your options would be to:
1. Swap in a dana 300, with changing the TH400 output shaft
2. Swap in a dana 20, with changing output shaft
3. Install a low range unit [if you dont have one], which is bolt on
4. Or do something crazy!
I dont know if you have seen or heard about it, but you can find everything you need to know about fullsized jeeps at www.ifsja.com
which is the International Full Size Jeep Association. Im a mamber there, with the same name. Hope ive helped you out!