A Body Small Bolt to Big Bolt

I've got a '72 Plymouth Scamp that I want to convert to the big bolt pattern. I found a late 70s Volare "Duster" with all the disc brake components still there. My question is are the spindles and everything going to match up to my Scamp? I know I'll need to pull the upper control arms as well.
Also I found a '67 Coronet parts car with an 8-3/4 rear end. I heard the '65-67 b body 8-3/4 rears will fit in an A body, but the perches need to be moved. Is that all I need to worry about for a rear end swap? I appreciate your time. Thanks

Yes you can use the disc brakes from the Volare/Aspen cars on your A body Scamp. Do not bother with the F body (aspen/volare) upper or lower control arms, they are very different and do not fit.
Spindles, dust shields, calipers, rotors, caliper mounting brackets, hardware. Get the master cylinder and proportion valve/distribution block with the connecting lines between them as well if available. I'd also take the brake hoses for comparison on the new ones you'll have to get.
You can get a ball joint adapter if you want to keep the upper control arms on your Scamp. You'll need the lower ball joints for a 73-76 A body.

You can use the B-body rear axle but it is wider then an A-body. You have to use a funky offset on the rear wheels to make it work.

I used the 1973 to 1976 Duster and Demon, Dart Sport entire front brakes and A arms and lower control arms and spindles on my 1971 Duster, everything bolts in except the later brake lines. I ended up using some later model (1980 or so)Dodge 1500, 2500 Ram Van front lines I did use the right spindle on the left side and vise a versa That mounts the brake calipers behind te spindles, moves the weight back and makes using the later Van lines easier The early B body 8 3/4, Pre 1970, are about two inches wider than the A bodys are

Cab he's got a Volare Duster for parts, F body not A body. UCA's will not fit, not even close.

Alright I really appreciate all of your input. I'll keep looking for a '73-76 I can pull control arms from. And hopefully I can figure something out for the rear end. I plan on pulling a 360 magnum from a '99 Ram and dropping it in my Scamp. Should make a fun street car.

Probably the best and easiest way to change out the back is to get a hold of Dr. Differential a Moparts member and buy new axles from him with the 4 1/2 inch pattern. Better axles than stock too.

The upper A arm from any 73-76 will work, whether they are from drum or disc brakes, all have the large ball joint you need for the F body spindles.

Your lower control arm should work, you only need to change upper A and spindle.

73-76 LBP 8.25" rears aren't too hard to find. Many 318 disc brake cars had them. Don't forget to pull the lower shock plates, if your 72 has a SBP 7.25" rear it will have 2.5" tubes and lower shock plates, you need 3" plates if your going to a 8.25" or 8.75" rear.

I make tapered sleeves that adapt the early A-body UBJ stud to the 5 x 4.5" disc brake knuckles.