7 1/4 rear end hold up?

i would at least go down to u pull n pay and see if there is an 8 1/4. i really doubt there is one there, but there are a couple of 84 le barons down there with 8 1/4 rears. measure them, they might be about the same.i am using my 7 1/4 with a 360/727 and its doing just fine, but i have half the horses you do. you can drive it around, but the second you really get on it , something may give.