budget build 360

No passport so that leaves me local. So stock bottom end,do I need all the machining or just an overbore. The reason I ask is half my budget will go into machining the block. I do at some point want to add a 100 shot of nos will the kb pistons work with this?
I wish on heads, I was going to get a set but they will eat up most of budget as it is I will have to wait and hope for a decent set of used to come along up here do to the border fees. I appreciate everyones advice so far.