Unless you just want the look do not bother with rear disc as the only benefit will be brake fad under hard braking conditions. Get some stainless steel lines to go from the hard lines on the car over to the front calipers and the one from the read hard line to the rear end hard lines. If the brakes are working well then use a quality DOT 3 fluid (Motorcraft, Wilwood, Motul, etc.) and flush the system. Have the rotors and drums turned or replace them with a quality brand like Centric and use some quality pads (PowerStop Z23's come to mind) and shoes (Bendix is what Maximum Motorsports sells).
Other than that you are just flushing money down a dark hole of no return. If the above does not get the job done then you just need to bite the bullet and move up the the SN95 brakes.