Chuck, Rack & Pinion is the way I am going because it was cleaner, easier, and allowed anyone to use any engine. A box could be made to fit, however would involve much more work. As far as cost, I bought a complete donor truck for $200, sold the engine, and rear end for $100, and I have the wiring harness, 4 good tires, T-5 trans, tilt column, swing pedals, drive shaft and box. So if you add up the costs of parts, it was fairly cheep. The rack was got from a local salvage yard for $35. It will need a new boot as I damaged one, however that is only $12
I do not see where the fenders would rub, however I have 26" diameter tires on the truck right now. Unlike a conventional S-10 where the tires hit the inner fenders, these are pretty cavernous. You could always change the offset of the wheels and move the track in or out as needed. I am running a big-bolt cab and front clip on Frankentruck however I will be running 10" wide wheels with the truck lowered, chopped, and sectioned.