Rebuilding and restoring the complete front fork assembly is easier and less expensive when new parts are used. Grab a pair while they are still available! Rubber items like these tend to degrade over the years, through general wear and tear and of course U.V exposure, so take the opportunity when rebuilding your forks to replace these at the same time. At this low price why put up with the worn out old items.
This Dust Seal rubber is a prime example. All rubber parts degrade and break up eventually.
While these are still available there seems little point in reusing the old parts