Swapping the 3/4 ton axle back in and perhaps a slight re-arch of the front springs, couples with 235/85/16 tires (approximatly 32" tall) should get what you're after. I would suggest a 16x7 wheel for best stability with those tires. If you're after disk brakes, you'll have to fab your own kit for that with 3/4 ton parts, but a few on here have done just that.
Here's a good thread on doing the fronts using late model parts, plus you might be able to swap to disk brakes on the rear using late model E250/350 van parts on the existing Ford rear axle.
