Magnum Shortblock VS. Non-Magnum

According to the Mancini site, they are all bored +.020 over..I thought they may be more than that, depending on what condition the block was in originally, but not according to the website. There is definately a balance difference, I forgot about that one..lol I dont know about using the GM arms tho..That's a new one to me. I guess at that point, you can use any ratio you want. I would have thought the heads would have had the rockers on them, just not rollers.