Parts are available. You will need deep pockets and a lot of patience to get it looking right.
Whether it runs right or need major work will not be known until you kick it over and comes to life.
My R69 sat idle for 10 years in 1990s, I cleaned the points and it was ready to go again.
The maintenance type of mechanics are easy. Most everything could be done with a screw driver and adjustable wrench.
This site will convince you you must immediately completely tear the engine down to replace the slinger.https://vintagebmw.org/forum/viewforum.php?f=7&sid=1eff2e6f8aa117b369f2f18537c5c4ac
I have 64K on my R69, that I bought in 1978, without a major problem and never even removed the heads. Still runs like the day I bought it.
As to the ride, my R69 has always been my favorite. I bought my V7 this year, and it replaced the BMW. Might feel differently next year about which is my favorite ride?