Well, I somewhat answered my own question. Apparently Jeppeson has some database cards for older GPS's...
One possible problem is how long the database will continue to be supported. I ran into this with my Garmin GPS-90, which is a great little unit, but ultimately Garmin/Jeppesen stopped supporting database upgrades because "they got too big to fit into the available memory" (or some such). Jep continues to offer the last available database (July 2002 or '03?) for the GPS-90 but at this date that's getting mighty long in the tooth.
So I guess you need to know not only that Jep has the database, but that it's really the latest; and then you have to be prepared for updates to stop at some (random?) point in time. But I agree that some of the old units really are capable little boxes.
Best