273 340 interchange??

Looking for some help here.Have a few questions. Probably stupid questions but need to ask. I have a chance to pick up a '73 340 std. bore bare block. Are all the 340 blocks(68-73) the same? What are 340 blocks worth? I have two '67 273's(one 4bbl. and one 2 bbl.) complete motors. Does the 273 4bbl. and 2 bbl. use the same crank? I was told they are both forged steel. Not sure.Thinking of using one of the 273 cranks in the 340. Will the crank from the 273 motor work in the '73 340 motor? Will the 273 crank need work? Thanks in advance.