Rebuild

I starting to look into rebuilding the old slant 6 just because there is no telling how many actual miles are on it and fix all the leaks with oil ect. My question is how should I do it. My goal is to slap a 4 barrel on and get a cam, headers and all the stuff that goes with it. Should I get it bored for this? Im really new to this engine stuff so I have no idea. Just trying to understand and do it way that is smart and not wasting my money on stuff I dont need.

Also what should a rebuild cost? I was quoted 3k with: Balancing, valve job, Magna Flux and some other stuff. It was over the phone so i don't have a list in front of me that would include all the stuff being done. I was told 1500 would be on a high side from others before calling this place, but 3k caught me by surprised.