Sounds like you're on the right track.
As suggested, I'd use add a leafs with your factory block.
I'm hoping that you'll install the correct control arms with your springs, you'll want to have the factory caster and have your axle centered, especially with nonstock rims. You'll also want to make sure your axle is centered under the frame, so you'll want the trackbar mount RC provides. This should eliminate scrubsteer interference with your aftermarket wheel/ tires.

Oh... you'll need to post pics when your done...