Roy,
I have a Daytona MIGI, I ran into the same problem with trying to re-index the torsion bars.
I looked on Samba for answers, people were installing Monroe MA 803 air shocks.
This works fine, I also installed a set of fill valves with air lines one for each shock.
I purchased these on EBAY, sorry I can’t find the original Part # for these.
I carry 60 PSI, left side and 50 PSI right side seems to balance the rear end.
Shocks cost about $55. on Amazon.com
Bud Hirsch