Weak-Super Slow Vacuum Wipers on a 68 Rebel 550

Electric wiper motors run in one direction, vacuum reciprocate, so the mechanism in the cowl is different. With some fabrication, a Jeep motor can be made to work.
The wipers typically use manifold vacuum and when that is low, the fuel pump vacuum section helps out. You can test the wiper motor with straight manifold vacuum. They should work unless the engine is under load, when vacuum is low. You could get a vacuum ball for a  few bucks at a junk yard, use a vacuum check valve, and run them off manifold vacuum. The reserve in the vacuum ball will get you past a short low vacuum time.
Wiper motors tend to have their grease get thick and then the motor gets tired.

There are electric vacuum pumps too that will provide vacuum for devices that need it... :-)
https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2380057.m570.l2632.R2.TR12.TRC2.A0.H2.Xelectric+vacu.TRS0&_nkw=electric+vacuum+pump&_sacat=6028

You have the good rebuildable fuel pump just get it rebuilt!
Same with the wiper motor.

Ron.

peter stathes does a good job...

A large vacuum storage canister will help, but only works for 30 seconds or so under acceleration. Usually that's enough, especially for a hobby car seldom driven in bad weather. Might not be enough for a daily driver, but many have used one in a DD. You can always link two together. Ford trucks used a half gallon "juice can" type into the 90s, so that's where I'd look. My brother's early 90s F250 has two under the hood. You will still need to have the vac wiper motor rebuilt. Seals get old, you know! With a new wiper motor it should be good for another 20-30 years.