Frank, I've had a few of them over the years, when I was a teenager, ragged the S**T out of a couple of them and never had a problem. Have one now in an 81 1/2ton with 185,000 mile , runs like a top uses no oil, doesn't smoke has a little valve noise but thats it. The oil was changed regularly and it has hauled boats, trash, broken cars and travel trailers. Wouldn't hesatate to get on the road with it.
If you're worried about the rpm's at highway speed ,try and find a 3speed trans with O/D, it will bolt right in, it is the same size,but you have to find one that is a late model with the syncronized first gear, a saginaw I believe. Look for mid 60's thru mid 70's car, they are kind of rare but you can find them. Think I saw one in swap section couple weeks ago.It will look just like the one in your truck( 7 bolts on side cover) where shifter connects.
Good luck.
