not trying to throw water on the fire, but wouldn't be easier/cheaper to find an a-body 8.25 in there. they are heavier than a 7.25 (but not immensely so), can hold up to all the abuse you are likely to throw at it with a slant or 318 and can usually be found just dinking around in boneyards....the a-body 8.75 has become like hen's teeth lately...if you have one, sell it to the highest bidder and that'll pay for your sure grip/set up costs/rear end and maybe still have some $$ left over.
if you have to cut down a b-body 8.75, costs can get high also. there are a few b-body rears that will bolt in just by moving your spring perches and carefully adjusting back spacing on the wheels...65-67 b-body IIRC.
if you are going to stay slanted, even with the T5, i'd go 8.25, but that's just me, not because of weight difference or parasitic loss problems, just cost and ease of finding the 8.25.
sb