70 C-20 stiffer suspension

[GMC69]

I have a 1970 C-20 that is sitting about 4" lower in front and 5" in the rear. Looks like it was done with drop coils and maybe one coil cut up front and drop coils in the rear.
I had to remove the bumps top and mount up front as it was riding on the stops when I got it.
What is happening is when I hit a dip in the road, I find the truck is too springy, feels like the seat belt is the only thing stopping me from hitting my head on the roof. I'm thinking that maybe the springs aren't strong enough for the big block and compress too much then rebound more that it should.
I'm wondering if stiffer shocks would help. Not sure if they are drop shocks or not currently.
The other option I was looking at was to go air bags on all 4 corners since I have coils all around.

I like the height it's at right now, maybe 1" higher up front would be ok also.