7260 big enough???

If I was buyin a driveshaft anyway then i would upgrade to bigger joints. My 366 spit a couple of those 7260s out, with 295/50s,a 3.55 X 3.09low, and no traction devices other than the pinion snubber.
My 1350s are still going strong.
The bigger joints require matching yokes at each end.
I think the u-bolts might be marginally stronger.
If you upsize, install the new yokes first, then measure and order the new shaft. Make sure the springs you plan to run are also on the car.