If your grandfather, L. G. Murray, was tying flies in the 30's, 40's and 50's, then he was a contemporary of another very famous Maine fly tyer named Carrie Stevens. Carrie, from Upper Dam, Maine popularized the Rangeley Streamer, which is a feather streamer characterized, generally, by paired feather wings, shoulders and cheeks. For a look at Carrie's streamer patterns, try the below link, it may help you identify if your grandfather's streamers were tied in the Rangeley style or if they were tied more in what people refer to as the New England streamer style.
Carrie Stevens' Streamer Patterns - Raske's New England Streamers - Global FlyFisher
There is a new museum that has just opened in the Rangeley area (see the link below). It's called the Rangeley Outdoor Museum and I would think that they would be very interested in the collection of flies that were tied by your grandfather and would probably exhibit them proudly. I suggest that you get in touch with them, tell them about your flies and see how they would like to proceed.
Rangeley and Oquossoc Outdoor Heritage Museum
If for some reason, they do not show an interest in these flies, then I'm sure that they could point you in the direction of some people who would be interested; including private collectors.
---------- Post added at 07:39 AM ---------- Previous post was at 07:01 AM ----------
Second message. A little more information for you, which may or may not be relevant; I have no way of knowing.
There is apparently a streamer called the "Murray". It's been recorded by Ray Bergman and there is a bucktail version of it that has been tied by a fly tyer named Monte Smith in the below link:
Bergman Conversions - New Streamers - Global FlyFisher
Scroll down to the 8th picture in this link and you'll find the fly.
If I were you, I'd have a look at your grandfather's flies and see if you can find one that looks like the one in the picture (except the wing is apt to be a feather instead of the bucktail in Smith's version). If you can, then that would be a very good indication/confirmation that your grandfather was a well know tyer (which fits with the fact that people used to order flies from him).
All of this would increase the value of the collection that you are describing; whether you plan to donate it or sell it to a private collector.
I'll see if I can find a picture of the Murray streamer in feather wing form and, if so, I'll post it to this thread.