magnum or pre-magnum that is the ?

If your converting an LA engine, it should remain balanced as such, the main difference between the 2 is from the top end, shortblock stays the same. If anyone needs there was an article in Mopar Muscle that explains the conversion, I can photocopy and send it to you. I can see if I can scan them for email...have to check. BUT you must have oiling through the pushrods, that is Magnum specific!!!!!!!