Why would you want to change the front to smaller brakes? The rear is a no biggie swap, but I don't get wanting smaller front brakes, especially since 3/4 and 1 ton fronts aren't any difference in bolt pattern or wms.
Re: the rear brakes - When I put disks on my 14B, I bought replacement rotors and calipers for a Chevy D-44 (any rotor/caliper from a '73 to '77 Chevy Dana 44 will work.) The brackets you need to buy to mount them can be bought all over Ebay, the Internet, the magazines, and undoubtedly through people right here. I got mine from Blue Torch FabWorks (http://www.bluetorchfab.com/). Fairly cheap and clockable, too. I'm sure you can find something similar for a D-60/70 if that's your bag.
I should add that there's something else you need to do or buy if you want an emergency brake. I think it involves using Cadillac parts, but I might be getting my answers crossed. Since we live in the frozen tundra, I don't use an emergency brake anyways...too easy for it to freeze, so I didn't spend any time learning about them. Far as my truck's concerned, the tranny hooks me up when I'm in PARK and I've installed a line lock to give me "stay put" confidence for when I'm crawling.
I'm still toying with the idea of putting an emergency brake on the transfer case, though. there's one (or two? one, I think) unused ports on my NP205 that's meant to drive a mechanically-driven winch...I could run it off there, I s'pose. If not there, maybe between the transfer case and the rear drive shaft?
Hell, I don't know where it goes. Is it obvious that I've never seen one of these? Yeah, I think so. I've read about them a bunch, but not one truck I've seen has one. I wonder why. Until I learn, perhaps I'll stick with the line lock.
This swap has become very common, with many companies making caliper brackets. You can use the gm 3/4 ton calipers or cadillac calipers. Using the gm calipers does not give you an emergency brake, and the cadillac calipers are said to have some problems with the self adjusting mechanism.
Line locks are not a emergency brake. If a line is cracked or ripped off the line lock will not work. It only holds the pressure in the brake line.
The line lock is handy when your out wheeling and you want to get out of your truck to look at something. I'd never use it for anything long term (and by long term I mean any time I'm away from truck.) Since I don't use emergency brakes (because of the chance of freezing shut), the line lock is enough.
That doesn't keep me from looking at transfer case brakes...
It's an easy mod to do, DaBruin. Don't hesitate. Hell, you'll probably cut 100# of unsprung weight getting rid of those huge drums on the 14B.
I have the disc brake swap on my 14FF. I also have a 78 dana 60 front (ford) with dual piston calipers. On the rear I used 3/4 chevy rotors, with calipers for an 85 3/4 ton truck (heavy gvw, there are 2 different 85 3/4 ton 4x4 calipers, larger piston in the heavy version)
I have run all different tires sizes, from 35 mt's to 37 bfg muds to 40 hawgs to 42 tsl's. Do the swap and dont look back, its cheap, easy, and I can lock up any of the tires I have ran very easily.
I would add an adjustable proportioning valve, to let off some of the rear brake. I have a crew cab short box (fairly heavy on the rear axle) and my rears still lock up easier than the front.