It's a little unclear as to what you are attempting to do......why are you asking about crankshafts and interchange?
.Krazykuda's advice to pull a main cap and a rod cap to read info on the back side of the shell is spot on. The markings will be date cod, and size. Date code is month, year ( 9-72 ) for example, size will be STD for standard, or .001, .010, .020, etc for under size. If date code is newer than 1972 means someone has been into the engine before you; not a big deal, it's a 40 plus year old car, it's kinda to be expected.
