Beautiful lil' truck! The Vortec is a good setup, relatively trouble-free, less boost than a Jimmy, but less stress on the engine. A 6-71 is too much for a 283, 4-71 better. Arkus Duntov put a 4-53 on a 265 back in 1955 or '56, and it worked great.
I've got 40 years on you, and yours is as sweet a truck as I've seen.