If you have a viscous fan clutch, make sure it's operational.
International makes a full sized radiator and intercooler that should fit. I know some guys in the school bus crowd have upgraded to it. I'd recommend measuring to make sure it will fit before buying, but most I've seen have upgraded without any problems.
I have the part #'s on file somewhere. I'll have to look.
But more often then not, the fan clutch is bad and that's why you're overheating.