I've put plenty of power through and 8.8 and never had a problem. It's a good differential. Basically a Ford copy of the 12 bolt GM, which has stood up to some serious abuse over the years.
Straighten the tubes, weld them to the center section and get a bracing kit from teamz.
http://www.teamzmotorsports.net/prod...zm-8.8-cbk.htm
Put better ends on them like a big Ford or symmetrical and 35 spline axles and the thing will hold up to a lot of power.