You should have at least 3" of travel up front. If you are at that point now, then messing with the suspension isn't really an option. A dropped axle is then your only choice. When using a dropped axle on these trucks, the pitman arm will need to be re-bent also, otherwise you will end up with bumpsteer if the draglink is not close to being level.
If the shock travel stops before the suspension comes all the way up, then you have a problem.
As for air bags, I believe Air Ride Technologies has a setup for live rear axles, which is basically the same deal as a straight front axle. But it seems to me to be a bad idea in that if you can aford to do air ride, then you could afford to stub the frontend with a Nova/Camaro or get a Mustang II kit and still have some money left over. Going to an S10 frame is also a very popular choice for the 47-54 trucks. Of course, none of this is "traditional" if that's what you're going for either. There may also be clearance issues between the bags and the steering. It would also look ugly. Just my opinion of course...
