I could have kept my stock pistons w/ 90k on them. The cylinders even had a decent cross hatch on them yet, so you might re-use the pistons! Bottom end was fine. Mill the heads a tad to bring the compression up a little bit. Get a dremel and spend 10 hours w/a porting book/manual, don't go crazy, just smooth it up a tad. 1/2 hour per cylinder will yield great results. And have a valve job done. My cam bearings collapsed when I took the cam out. So plan on those, and an RV cam....I'm looking at you for specs here shawn! A modern ignition, used dual plane 4V manifold, re-manned Holley Avenger carb, and free flow exhaust should get you to 250+HP. Double-ish a stock 304. And a really nice grin when ya get into the loud pedal!
Just my rambling 2 cents for a lightly warmed over, reliable, DD engine.
Of course THIS is the engine I should have built. But I got the "for a few bucks more, I might as well".....and "W/THIS combo I bet I could break 400hp!". DOH!
I say go for it, keep it modest and do as much as you can yourself.
I've also learned that sometimes... when people don't agree with you .... its best to hold them down and kidney punch them till they agree with you