Front Disc Brake Conversion Confusion

Thanks, Doc. I'll have to call them (and PST) for details.
They look the same, except Dr. Diff has no MC for A body w/ man brakes (mine), no control arms and ball joints, and no adjustable proportioning valve, unless the distribution valve is for that purpose. If that's the case, it won't work because my GM rear drums will require adjustable F-R bias.
The $435 goes up a bunch when I add the items PST includes.
PST has free shipping, Dr. Diff $293.00!

I stock everything you listed, and much more. USA ground shipping is not $293.

Stage 1 brake kit $445
10.95" Front Disc Brake Kit (Stage 1)
Adjustable prop valve $35
Adjustable Proportioning Valve
A-body front suspension kit including assembled upper control arms $335
Mopar Suspension Rebuild Kit
Aluminum master cylinder package $95
Mopar Aluminum Master Cylinder Kit
TOTAL $910

Of course many options are also available such as Hemi booster assemblies, suspension hardware, drilled/slotted/plated rotors, stainless flex hoses, pre-bent brake lines etc...