There are a few solutions I can think of. One of which involves modifying an exhaust header on that side. Do you have room to cut the offending exhaust primary and use a J-bend to cut and weld a path around the steering box?
The other solution would be to move the steering box. You might have to do some inventive engineering. But if you look at a late-60's Chevy or GMC, the steering box is similar in design, but it's on the outside of the frame rail, actually IN the wheel well. I don't see why that wouldn't work on my '52 GMC. I've compared trucks side by side, and with minor modification, (which you're doing on your truck anyway), it could work. Look into Flaming River to get a U-joint for your steering shaft.
