I wouldn't go any smaller than 33 x 12.50 x 15. You've got 4.10s so you'll be fine with 33s. A set of those Currie +3/8 lift shackles are decent (albeit expensive), and won't gank your steering too bad, and a 1" body lift would also help. If you're going to be driving it on the street a lot, the BFG MTs are great & not too expensive. Mixxis & Pro-comp aren't too bad, and if cash is no option, Mickey Thompsons or Toyos (Toyos have big fat sidewalls...nooiice). If your Heep is strictly a trail rig, with little or no street time, then anything made by Interco (Super Swamper) except the Thorn-turds, are great.
As far as wheels, it's hard to beat a cheap set of black steelies. About any of the brands are similar, and they're about $50-70 each. Stick with a fairly shallower back set of around 3-4" will help keep the treads off the springs & front end components.
Good luck, and keep us up to date on the progress.