Advice on which heads to use. 360 , 302???

Backyard mechanics solution to not having an air compressor to close valves. Get a length of cloth clothes line. Shove a bunch in through the spark plug hole with the piston at BDC leave some hanging out, rotate the engine around until the piston in that cylinder locks because of the interference with the clothes line. Remove valve springs and replace them. The clothes line will keep the valves from opening. Back off crank and pull the clothes line out. Move to the next cylinder.