I'll take the "rodding" side. After owning my truck for almost 20 years, and having it sitting in the garage most of that time because I could'nt keep it running for more than a couple of hundred miles before breaking down, I finally broke down and changed to pretty much what you are leaning to; V8, automatic trans, disc brakes in front, power steering, and highway gears in the back, and I left the stock straight axle.
I'm sure I've driven it more in the last 6 months than I did in the last 10 years. Besides being easier and more fun to drive, I don't have the anxiety of wondering if it will make it home or not.
And besides driving it more, I'm enjoying working on all of the things that are within my ability to fix.
I think 200 or 300 miles a week is a lot of miles on that old of an engine, and most of us are too spoiled by todays maintenance free engines to want to do all of the oil changes, valve adjusting, etc that go with a 70 year old motor.
