Listen to Tony Smith; he is one of our best gurus.
I would prefer not to have the term "guru" used - i am not in the same league as people like Snowbum, Mark Morrisey, Ray Peake etc. i will admit to having opinions and not being afraid to share them :-)
I believe that the 1980 models are iron (rather than the much more desirable "Nickasil" barrel engines) and thus it is much more likely that you will need to replace rings and bore the iron barrels. I also believe that the bike can be saved, but there is a point of diminishing return. You might be better off looking for an '81 or later in your area.
There is nothing wrong with "iron bore' cylinders, I was using a set in my 84 R65 when it was still an R65. If I were to persist with a set of iron cyclinder i would use them until they needed a rebore and then have them bored and nikasil coated - this is now marginally cheaper than buying new nikasil barrels.
My concerns with the 1980 model are - they have suspect valve seats and also the smaller valves. It is probabyl cheaper to buy a 2nd jhand set of later heads and refurbish them. BMW do not make "lead free" seats for the small valve heads, they can be obtained elsewhere, but as someone else commented - the cost ramps up.
The 1980 model has the heavy flywheel and the longer input shaft, the jury is still out whether the skeleton clutch carrier is a real improvement or not, but parts specific to the 79/80 model R65 are going to get harder to find sooner (for instance try and find a 79/80 side stand bush - they have the same part number as the later models, but the later part doesn't fit). The 1980 will have the round master cylinder, which in the absence of a source of new tanks is just junk, also it may (probabyl will) have an ATE caliper - againt he cost of refurbing this is about the cost of buying a brembo, so its junk.
To be honest, I'd take it on as a project, but I would not pay more than $500 for it. By way of comparison I have just bought a K100RS with a failed alternator for $400 and ridden it home. It has given the previous owner a few problems recently and the charge light coming on was the last straw. Old bikes can be very frustrating. you need a modern one to take your aggression out on.
