I too worry about the availability of motor mounts.  I recently saw an
Ampico that had been somewhat restored, and the motor mounts had been
replaced in a fashion I had never seen before.  The restorer used a
strip of appropriate replacement rubber and had wrapped it around the
rods of the system and then screwed down the brackets over it.

With the proper rubber, it seems like a possible solution.

Jeff Davis
In sunny (for once) Seattle, WA