Andy --

You can buy new rubber (and urethane) bushings for bugs, I would hope you can
for busses too. r and r-ing the bushings would probably do more for you than
the swap.  You might want to relocate the anti-bottoming-out pads to the
other side if you switch.  It looks like a few minutes with a die grinder
would free the cups from their present location and let you weld them on the
other side of the arm.  Ditto for brake line clips. 

Other possibilities: How is the rear alignment -- toe out or in?  Even if it
is set exactly where it was before, it might not have been correct before
either.  Toe and camber adjustments can interact.  

How is  the ride height at the rear?  Does it match the specs?  What are the
camber settings now?  More than a degree or two negative?  Are they within
spec?  How about your rear tire pressures?  Could you up them a few pounds
(or metric equivalent) and still be within the specs of the tires?

Roland Wilhelmy
65 bus plus rear suspension from '71 
(waiting for BusBoys' new IRS conversion
kit)