273 rebuild

I wan't looking for more cubes I just thought it would be easier to find parts for if I went to 318 but I guess that is unreasonable. I thought the 273 to 360 had the same block but I guess not. I don't know alot about this stuff but I want to rebuild my 273 which is a 64 model so I can keep it #s matching. I don't know if a crankshaft from a 318 will fit or if it would push the piston too high. It would be nice if someone has done this before who could help me out. I suppose I will leave the valves or just replace with the same size so I can keep the heads.