hopefully getting 4.10's

Hey guys im new to the site, just like to say i have been reading the stuff on here for a while and yall have some good info. I drive a 98 chevy 5.7L vortec with a 4in lift and 33x12.50 for now. i am looking to add another three inches or so, but i was wondering how i could do it, besides a body lift. I was looking to put rear add-a-leafs and maybe a shackle. but for the front in not sure, i was think maybe aftermarket re-indexed torsion key (dont really know if this is the best idea). I was to ultimatly fit 35's but i would like to re-gear too (thinkin 4.10's) but i was wondering if i could put a 14 bolt in the rear, not sure if this would work though with out upgrading the front. Can i just put 4.10's in the stock housing.

(i know i have to regear both front and rear at the same time though)

any imput would be greatly appreciated,

thanks kinda new to all this stuff just want to do it right, cuz i have almost 250,000 miles on it and i know the engine and tranny are going to be going soon even though they are doing fine now.

thanks
-chris