What's the goal... to have the (lower) frame rails level with the ground? If that's the case - you really should consider the size of the REAR tire. Also- I'm assuming your getting a rigid frame?
I've got a rigid with 33* rake, running a DNA (-2) springer front end. 21" spool hub up front (with a Speedmaster) and a 18x5.5 (180mm Metz) out back. I ended up flipping the rockers to get the frame rails level-er, but it was close without it 'em being flipped (see my gallery). Don't quote me, but I thought stock was 24" or 25"?
the rear of my fame is dropped 4" running a 130-16 rear tire and i have a -2" DNA springer with a 21" stock HD front wheel and hub. looked good as is but i too flipped the rockers to level out the frame rails.
'73 XLH rigid, nothing has gone untouched