I agree, i think a 8 3/4 with GOOD pieces in it will stand 600 horsepower, with a mild converter, moderate weight, and bias slicks or et streets. (Radials demand a dead hook, bad for weak rears)
Op's truck is not someplace I would gamble on an 8 3/4
Edit: forgot to mention, "with an auto trans", but I guess that's implied by the converter comment.
