Front Suspension Upgrade...

Uh something don't sound right. ALL Mopar torsion bars should have 1.25" hex ends. All of them. (well not the silly F,M,J Body bent ones) ALL A-Body bars are 35.8" long. The last 3 of the part number should be on the bar ends should tell you what you have:
2535888L/889R = .830 Slant 6 Bars
2535890L/891R = .850 Base V-8 Bars
2535892L/893R = .870 HD V-8 (340) Bars
2535894L/895R = .890 Big Block Bars

All A-Body lower control arms are interchangeable.

I might have a spare set of .850 bars around somewhere.

To swap on the disks, you just need to swap the upper arms and the spindles. Assuming what you got was indeed 73 Scamp parts...