I am going to jump in here just so someone with way more knowledge on this can tell me how I am wrong and give you better information.
I have a '77 2wd and am trying to do the same thing. Mine came with stock 5.5x14s. So I was limited in size by tire manufacturers. I have 205 70/r14s right now. Which comes to about 25.5 inch diameter. I lifted the truck with the torsion bars in the front and a shackle lift in the back. Got about 2 inches that way. I wanted more so started looking at new wheels to fill my now-more-vacant wells. I ended up getting some 7x16s from a Tahoe. That opens up a lot of different options. (Then again so would some 15's.) The 7 inch wide wheels do require a spacer, but only about an inch. (1 3/4 in the back to keep the width the same in the front. I am wanting to go to a 215 70/16 which gets me close to 28 inch tires, but now a fever to cut the fender just enough and go for the 30 inch tires.
My only regret on the Tahoe wheels is they use a bigger wheel stud. (M14 x 1.50) Chevy Colorado wheels use the smaller Luv wheel stud. (M12 x 1.50) I am just going to have to drill and push in new larger wheel studs.
The wheel lug spacing on the LUV should be 6 x 5.5 (6 x 139.7) unless someone has already done something there.
Good luck and if nothing else, I hope one of the more knowledgeable guys can either confirm my info or school us both.
Jason