340

Unless you are doing a numbers matching car there's no need for the 340 block. A 360, punched to .040in and a 318 crank will get you there. But why do that when you can do 368 ci or more with the .040 bore and a stroker crank. Just thinking.
FWIW, a 273, 318 or a 340 crank will not drop in and work in a 360.