I've done a bunch of conversions using the kits that Ray fabricates. They are great. Very high quality of workmanship and wonderful customer support. Ray is headed back to Thailand at the end of July, so if you want to order a kit, you need to contact him ASAP.
Putting discs on the front only will improve your braking dramatically, enough so that you can toss a person through the windshield if they aren't strapped in...
Put them on all four corners and you can stop doing the biweekly brake adjustment and can enjoy picking up innexpensive brake pads at your local parts store when it comes time to refresh the brakes...
I've got the discs on all four corners of all my M37 varients...
On the front, everything is a bolt on. After you send off your hubs for some machine work and get the hubs and the instalation kits back, you source the rotors and loaded calipers locally (I always ask for '78 Chevy Silverado 3/4 ton 4x4 when I walk up to the counter, it makes it easier for the guys at the parts store to find what I am looking for...) and bolt everything up. If you are doing the rears, you will have to blow off the rivets holding on the brake backing plates instead of unbolting them but otherwise the instalation is the same...
Ray moved to Thailand a couple years ago to allow his wife to be closer to her mom...