This is my favorite mod....if you cannot weld, simply take the rear housing to someone than can. IMO, you get the most for the least.
On the front, a set of Wilwoods is my pick. You can now keep the front hubs tucked and they come in a dual 4" and 4.5" bolt circle....win /win. For a few bucks extra, you can get them out of the box powder coated and with cross drilled rotors. The 4- piston calipers and brackets are very lite weight comparred to the bricks the 73 and up A body single piston calipers /brackets.