NO, your U joint should match up fine. A regular Cherokee (not Grand) would be a better match, as they had drums (no proporioning valve issues) and leafs rather than coils. Ive seen Dana 35s, Dana 44s as well as the good old 8-1/4 under them.

90% of /6 powered cars out there are fine with the 7.25 rear assuming minor bolt on mods and no drag racing.

for the remaining 10%:
9% could use a 8.25 rear and the 1% that are tweaked hard core and raced periodically could actually NEED a 8.75 rear

fact is it costs big bucks to build a 8.75 rear . i can speak from experience because i am building one right now(for my 340 stroker duster) here is the price break down: $200/housing + $250 powerder coating + $350 loaded dutchman large bolt pattern axles, + $350 TSM disk brake kit + $100 742 housing(powedercoated) + $400 sure grip + $200 gears +$90 master overhaul kit/seals etc... + $70 ubolt yoke.

add it all up, it costs a lot of $$ to build a 8.75 rear. but for some reason everyone wants one, when in reality a 8.25 rear will hold up behind a 440! currently i have had a 8.25 rear for sale for a while...everyone wants it, but no one wants to pay for it, they think because its not an 8.75 rear that its worth less. i know what it costs to build a 8.75 rear and convert it to large bolt patter, so the $400 for a basically bolt in 8.25 rear is CHEAP!

if you could find a bolt in 8.25 rear i would go for it. if they are hard to find, try to find a bombed out parts car with one. thats how i got mine...and it had a NEW posi and a new set of gears! other wise your going to have to find a complete 8.75 rear that has already had a LBP conversion, and used i have seen them in the $800++ range. around here a complete a body 8.75 rear drum to drum with small bolt pattern and no posi goes for $500

I agree with the above Guest that most people don't NEED an 8 3/4" behind a slant, but most like it because of the gear interchangability, not just because of strength.

Also you said a 8.25" will hold up behind a 440... well, I guess it depends on your style of driving and setup, because I've heard of more then one tale on moparts.com about people stripping all the teeth off their ring gear on an 8 3/4" with their big blocks.