Hey Phoneman! That sounds like a hell of a prize to win!
Best I ever got at such an event was like a t-shirt or maybe a little after dark action from one of the gals workin' the beer tent!
Most of the vehicles i've owned in the last 20 years.. the ones that actually could get up to 100MPH, anyway.. had no vibration and tracked straight at those speeds.
Get going about 45mph and yank a sharp left, and that's where you start separating the men from the boys.
But with that said, speed limit around here tops out at 65mph.. and I don't guess i'd need to go any faster than that with a load of hay or plywood in the back of the truck.
In selecting a frame for your truck, it all boils down to what you want your truck to be when it's done, and what kind of budget you have, and how much time do you want to spend monkeying with it.
I'm perfectly content having my 57 year old truck ride and handle like a 19 year old truck, and sit up off the ground like a truck should. and i'm perfectly content with a humble 4.3L V6.
For guys like me, on a low (or no) budget, bagging an old s10 with a shot to hell body but otherwise running decent for around $500 is a perfect donor chassis.
For dudes into high performance, or interested in lowering/airbags or that sort of stuff, a fresh chassis engineered specifically for those applications in mind would be the better choice.
Provided they could afford it.
That's a pretty cool old phone truck you got there! I don't suppose he left his butt set under the seat, did he?