[jflem3]

What size Rims are you looking for? and are you going to be running low profile or an All-terrain tire.
I had a set of Mickey Thompson Classic 2's on my 3/4 ton burb in 17x9 with 275/70/17 Goodyear AT/S's they were 32.3" tall.
Enkei Makes a really nice 20" 8-lug 5-spoke that I used on a Suburban We just finished for the SEMA show in November, It has enough GVW rating.

Axle Options : another option is to locate a rear axle from the late model GMT(800) Silverado, Sierra, Yukon or Suburban.
A 1/2 ton axle has the same (GVW) rating as the 3/4 axles of the 67-72 series trucks, or if you want a heavier duty axle, light duty 3/4 ton axle it has eight lugs but its a semi-floating axle and you could redrill the bolt circle. To top it of they have rear discs (big ones)