Where did you get your front disc conversion?
My first dart I bought a whole valiant sedan for $200 like you guys, and I kept the engine as a core for my wife's Dart. For my current Valiant I found a set of the spindles on CL for $100 but I had to drive pretty far to get them. I bought new UCAs and BJs on ebay ($250) and new calipers, hoses, pads and wheel bearings ($160 though I could have used the old stuff). Not including the suspension rebuild and alignment I was only into it for $500 or so, with the new LCA bushings, new pitman arm and labor to press bushings it was still under $600.
I think anyone could duplicate that. I've also seen links to the OEM (MP brakes) kit for pretty cheap.
Personally I would not go scarebird because the stock drum spindles on the 9" drum cars is scary weak, plus any car that old probably has one or more bad balljoints so you will be doing the work twice otherwise.
For the socal guys keep looking at the yards in Wilmington - I've seen three cars with LBP discs in the last six months. About $125 for all the parts (spindles, calipers, ucas) - less if you leave the calipers behind and just buy new ones.