I have an "85" and had my tanks rebuilt with a 3 row core. The extra room that the third row took up made my stock fan RAM into the rad on its first off highway romp. I had to go to an electric so this would not happen again.
1. New cap, I like the 'Stant Lever Lock' You can open a system that is hot if you need to, and makes burping a little easer.
2. New thrmostat, cheep why not.
As for belts, hoses, water pump, its your call if they look/feel bad and you got the $ swap them out, if there in good shape, run them.
Flush the block w/ clean H20, you dont want any crap in the new rad.
Ted