360 magnum. 1 piston lower in cylinder??

Does anyone know of an accurate way to check the crank for straightness besides what I have already done? I don't have access to a lathe but I suppose I could rig up some sort of jig and dial indicator. Maybe a straight edge across the length of the crank at the journals? Remember.....previous owner said he heard the engine running fine before it was pulled but I only have his word.