HI Lotshorses
You said in your original post you want to be able to drive this thing on the highway....if that is the case...upgrade everything you can afford to upgrade...in stock form in a typical traffic flow situation you are asking for trouble if you upgrade one thing under the hood but not under the fenders too....these trucks do great at there original pace (so I have been told) but if you jack up the horses under the hood do yourself a favor and put disc brakes on the front too. There are several vendors that sell them out there now...suspensions I would say would be up to you and how rough a ride you want....these things dont ride anything like anything we daily drive now.....they are old trucks...
If I was younger I would do a full chassis swap and be done with it...then everything works like our current day stuff...but you still have the cool old truck looks...but then thats a whole 'nother can of worms to be opened..
my 2 cents
MikeC
