Thats not quite as easy question as it would seem.
However, if the truck performed well with the converter you had, then I would consider going back with stock if the engine is stock.
But since you increased tire size over stock, you might want to go with a slightly higher stall speed to let your engine develop more torque.
Here are a couple of links that explain stall speed fairly well so you understand how different gear ratios, tire size, and even slight engine mods can affect your choice.
http://www.carcraft.com/techarticles/selecting_right_torque_converter/index.html
http://www.hardtail.com/techtips/selectingconverter.html
The problem with these articles is that they are for street vehicles and are concerned with getting off the line and highway driving.
You want to do all that too, of course, but in your case if you need higher engine rpms for more power during rock climbing or heavy mud, you can just go lower with the gears.
Basically, listen to the guys here who have trucks like yours and who have changed a lot of TCs.
But read the articles so you will be able to follow the reasoning.
Personally, I think that your best bet is to set it up for good highway performance and let the gears take care of the off road stuff.
You can pretty much get any engine RPM you want at any MPH with the right shifting.