Vortec's are great for street and mild strip use. They use a different intake than old SBC's. I put vortec heads on my 84--big difference. The only downside is they cant handel much lift stock--.470" max. Add comp cams beehive valve springs and .100" taller valves and you good for .550"+. They come with 1.94/1.5 valves. The vortec's flow better untouched than earlier heads that are ported. That block is factory Hyd Roller. Thats worth a big HP gain over a flatt tappet cam. To be short, a vortec motor with 10 to 1 comp, headers and the right cam and intake will be an easy 400HP.
If it were me, I'd rebuild it with flat top hyperutetic pistons, LT4 hot cam, and Performer RPM and 750 CFM carb.