It's not quite as simple as putting an airbag into your steering wheel.
There are sensors in the bum-er that measure deceleration which trigger deployment of the airbag.
There are all the electronic controls, as well as electrical connections.
And then there's the collapsible steering wheel with the airbag mounted in it that is unlikely to mount on your existing steering column.
You must also consider that airbags are one part of a safety system in a modern vehicle. That system includes crumple zones, a rigid passenger compartment, breakaway components, and so on. I think it's pretty obvious that your '46 doesn't have any of this modern safety innovations.
I truly believe that your best bet for an airbag is a balloon mounted to your steering wheel, the thicker the better. Perhaps one of those punch balls would work, although they are kind of large.
My female counterpart suggested an emergency raft mounted to the dash with a handle to pull for inflation. That will offer some protection for both driver and passenger.
No offense, but we both had a good chuckle at your (or your wife's) expense. We also believe your wife needs to learn a bit more before making such suggestions about how to improve your truck. I'd rate the project of putting safety airbags into your truck in the extremely difficult to impossible range, leaning to the latter.
Now, if you want power steering parts, any auto parts store will have the power steering parts (pump, lines, rack, etc.), but you'll have to do some re-engineering to make it work. There are other vendors that make a complete kit.
I'd check with Chevy Duty, LMC, No Limit and other vendors that have PS kits with all the compnents needed to fit in your particular truck.
