I think the easiest way to cut out the centers is with a plasma cutter. Jthomas on here has one and could cut them out for you plus weld in new centers. I would not go with flat plate centers. I suggest getting pressed (dished) factory style centers. They are stronger. There is a dude on pirate who sells them now. I've got a set of 12 bolt H1's I have been getting ready to put together too. John Thomas cut out the centers for me, I bought the pressed/dished centers from MRW, but the guy on pirate is cheaper now, and I bought my rock rings from Copperhead fab. I still need inserts, and will probably go through Stazworks for those. Well, that is my 2 cents. Hope that helps.