I'd recommend looking through this site first and seeing what others have done because there are a whole lot of options. When you say conventional, I assume you want to move away from the NDT's (stock) to something with radials. Do you want to switch the wheel and tire or just the tire? Do you want to stick with duals on the back two axles? Dangerous and scary as they are, modern trucks use lock ring wheels all the time. In fact, you'll have a hard time (maybe) finding some shops that will work with the military 2 part wheels - at least in my area, many will not.
If you have money to burn and no time, you can start with vendors like Eastern Surplus (not a bash, I buy from them myself, but they are not the cheapest - and shipping to CO won't be cheap either).