If your car hauler is 2500 pounds and the car about 3500 to 4000 you should be ok for 100 mile or less trips.

If you have the 9 1/4 rear-end, you're good, the 5-45rfe, they're bullet-proof, and the rad opening is fair sized, it should be all good.

You have the right idea, so just take your time. If it shifts alot, lock it in 3rd gear (direct) and you should be ok.