[RICK LAKE]

Lippy It's the torque load that can cause a jag rearend to break no how much HP you are pushing. I used all better parts for my Jag rearend from CWI. Better Locker, 30 spline chrome moly stub axles, rear cover cap support cover the differential carrier caps to stop walking.
Alot depends on what tires you are running? BFG on the car, you will not hurt a thing. Nitto N5 in a 315 size, will put a load on the drive train more than BFG's. I would tell you to have the rearend built with 30 spline setup with cover and catch tank and not to worry. Avons are a good sticky tire when hot. Over built the car. This will give you piece of mind when playing. Other side note, 3.54 is alot of gearing for a 600HP motor. You didn't give the first gear ratio but if it's in the high 2.70 and up, you will never use 1st gear. Drop the gear ratio to 3.31 or 3.07 for all around better driving. I run 3.31 and the car hauls hard. Rick L.