I know what you mean about finding homes for those old 78s. A number of years ago, we also had to "find a home" for a bunch of 78s from our grandparents day (as well as a bunch of 45s and 33⅓s, and record players to play them). They'd probably be worth a small fortune today, to some sentimental collectors.
Not sure about this, but I believe Fiji Hill might have a collection of historic 78s, and I bet he could probably direct you to somebody, or some web site, or place, where you could find a new home for your collection. (Good luck with that effort.)
(Do you remember this song on a 78?)
I used to acquire my records at swap meets and stores that cater to collectors. The only store that I know of that still does so is Canterbury Records in Pasadena, California, but I haven't been over there since Frbruary and don't know if they survived the COVID lockdown.
For years, I read Goldmine magazine, a print resource for collectors. Its website contains links to collector sites. href="https://vinylradar.com/vinyl-record-marketplaces-best-places-to-buy-rare-vinyl-records-online/">Vinyl Radar,/i> is an online collector's site that might be useful.
Good luck in finding a home for those records.