The 2 biggest probs with trucks, as far as handling are front weight bias (with the result: a very loose rear end if not weighted down with something) and their tall "stance". There are kits/parts that will drop this truck to where it scrapes the pavement, then it's a ,matter of adding those aforesaid sticky tires (A good think about trucks is they have huge wheelwells.) and good springs and shocks or as already said "bag it".
The front weight bias? Well, there is alot of fiberglass available to get weight off the front (fg hoods, fenders, doors?) and that is certainly cheaper than relocating the engine and tranny.
I'm surprised, most mid '70s Chevy/GMC pickups I see are very rusty, especially the hoods and rockers, to the point that they are somewhat rare here.