I pretty much agree with everything you said above, except I would have been for keeping the 8-3/4. That's just me though, I usually prefer a lighter part if the lighter part can get the job done.
I should add that my personal car has 28spline axles in a chev 10 bolt, also a 2-1/2"x.065" driveshaft. I usually don't even bother to tell anyone though, usually sets off BS detectors when they find out it's been 5.73 w/ a 1.30 60' way back in 2011 when it had 700whp. Even more power now, still dead hooking radials with the same axles and driveshaft.