Welcome, JD! Glad to have you as a member! [smiley=thumbsup.gif]
Lots of knowledge and experience with the R65 from people who hang out here. Our moderator, Rob, happens to have a 1979 R65 that he bought new back in the day, and probably can answer most, if not all of your questions. I'm sure you'll hear from him soon, most likely, since he checks in fairly regularly.
See if you can find out how many previous owners the R65 you mentioned has had so far. That might give you an indication if it's been taken care of or not. The more hands it's been passed thru, the more likely it may have been with someone who may have neglected it. If you can find out its maintenance history, so much the better. If it has been maintained on a semi-regular basis, the number of miles isn't that big a deal. My R65 just turned 141,000 miles on it, and it continues to run fine. (Of course, I've spent a great deal of money replacing stuff on it that wore out over the years, too!)
What model of "newish" BMW do you have right now? Are you planning on keeping it if you buy a R65, or are you going to sell it?
The R65 is one of BMW's most underrated and (in our opinion) underappreciated bikes in their long and glorious history. They may not be the fastest or best handling, but they seem to do most everything quite well. I think you will love owning an R65!
Keep us posted on the bike you are interested in, OK?