Just be mindful that these trucks are definitely not what could be considered power houses.
If you up the size of the wheels/tyres you will get better speeds on the highway, but probably only on the flats. When you hit a hill you will know it, as you will be dropping down through the gears. Speed daemons these trucks are not.
The off-road capability can also be affected, as your gearing will not be as low as it is on standard sized tyres.
Having said all of that, putting 37's on these trucks is common here. On my truck I run 35.5" tyres, which I consider to be a "best of both worlds" setup, for better highway speeds while not losing too much in low range.
@Aussie Iron (Dan) can probably give you more information on what works and what doesn't, as he is much more familiar with these older trucks than I am.
As for the rims... other than fitting an appropriate 5 bolt centre, can they change the rim offset too?
If you don't know, the super singles that are normally fitted to these trucks modify the track so that it is the same for the back and front, which is better for going off-road.
You use the same rim front and back, which means that they get flipped. The front rim is mounted on the deep side of the rim and on the rear the rim is mounted on the shallow side.
I'ts definitely not madatory to have the same track front and back, but it is better if you do. That's kind of the point for changing to super singles.