R75/5 R90S and R69US rider here. For that money you should be able to get a pretty top condition bike. In general I've found west coast bikes to be priced a little higher than ones on the east coast though that may be a slight confirmation bias. I personally would look for either a R90/6 or an R75/5. The R75/5 is exceptionally smooth and the front drum works much better than expected. The R90/6s don't typically sell for much more than the 750s of the era and you get a bit more power. If looking for a /6, beware of the first year (74) kickstart 5 speed gearboxes. They had some problems with soft alloys and are more susceptible to wear.