My 46 2-ton that was still running the splash lubricated babbited rod bearings. It could run up to 55 comfortably on the interstate. I had it 63-65 a few times, but it didn't feel right! 55 wasn't bad. I had rebuilt the engine with .030 over pistons. Everything else was stock internal and only upgrade to a Bosch blue coil externally. Stock induction and a 2 1/4" exhaust pipe on the stock manifold. 8.25 tires in the back with a single speed rear end.
Gotta make sure the thing stops and steer's as it should first. If you want a faster driving truck, consider a chassis swap. I'm not a big fan of that, but it would be an easier way to go to just put your cab on another chassis!
I also routinely had the bed loaded with 8,000-12,000 pounds worth of steel. It was comfortable at that, but would only reach about 40...
Decide what you want the truck to do and plan the build.
