Wait now, the 4.5" flip will give you 6.5" of lift with your 2" lift springs. I don't think that's what you want. Could you rustle up some stock 52s from the junkyard? They may flex/ride better than the lift springs you're running now, and they would give you only 4.5" of lift.
I'm not familiar with the DIY flip, but ORD has a 2.5" flip that would compliment your current front springs, I think.
Come to think of it, you can use 54" rears with the ORD flip. I don't know if Kert's kit can do that, but that's what I would do. Stock 54s with a 2.5" flip and 4.5" shackles.