Welcome stepdog.
Wow, you're a patient man, doing your upgrades in the 70's and still not on the road. Hopefully you're getting close to enjoying driving it.
Mono leafs are o.k. and they will give you a 2 to 3" drop. They ride a little stiff but then, so do the original springs, eh? (In my best Canadian accent). Posies make a 2-leaf lowering spring that probably works better, I think Speedway still carries them. As far as the master cyl/booster, a lot of folks run the firewall mounts but in my opinion they just don't look that great. If I ever decide I need power discs I'll go sith a frame mount set-up, but again, that's just my opinion.
Good luck with getting her on the road.
