70 Duster--conv. to 73-76 front disc??

My '70 Duster, pictured top left..I currently have the standard front disc, rear drum brakes, manual steering box. Of course, without saying the 70-72 kelsey hayes front disc setup sucks. Its expensive, and thats available is rebuilt at the parts stores. Nothing aftermarket that works w/sm. bolt pattern and stock factory original setup because it sucked so bad.
The pitman arm is in bad shape, so just ordered one new from Just Suspensions.To avoid additional co$t, Im staying w/stock pitman arm. I asked about my "braking" options and he referred me to Wilwood. He said to keep cost down and stay sm. bolt pattern I can convert to the '73-'76 style front disc and keep my spindles. He said the aftermarket calipers they make for this style work fantastic.
This is a project that needs attention by this autumn, and any feedback I can get from you guys would be great. Im sure someone has upgraded to this setup, and kept the sm. bolt pattern intact. For me, $$$$ is an issue. No way am I investing over 2 grand front and rear just to fit large bolt pattern wheels.
Exactly what is involved with this conversion?