76 Dart Front Big Bolt Pattern Disc Brakes on my 66 Valiant??

You need the upper control arms off the '76. They'll bolt onto your '66 car and accommodate the '76 knuckles. You can keep the '66 lower arms, but probably best to go ahead and get the uppers and lowers out of the '76, go through them with new bushings and ball joints, and install them on your '66. Go back to the yard and get the power brake booster and brackets, the master cylinder, and the combination valve/distribution block. You might not want to use the booster (in which case sell it w/brackets to someone on here who wants it) and if the master isn't nice and fresh you might want to leave it behind and buy new. Be advised these '73-up disc brakes have a larger wheel bolt circle than is presently on your '66: 4&189;" versus 4". So you'll need to swap on some appropriate wheels. They need to be at least 14" diameter; 13" wheels will not clear the disc brakes.