No, the R65 is not a slash model, though varous parts are interchangeable, there are different clutch and throttle and choke cables for the different handlebars heights.
You will need the new upper brake line as you surmise.
You will probably need a new shorter clutch cable depending on how much shorter&closer together the controls will be on your new bars - the clutch cable has to be smoothly routed with no kinks or sharp bends. The same can be said of the throttle, chole cables (I think your model has (2) coming from the bar to each carb). On the later R65 models, there is a single cable from the bar to a splitter junction under the tank, which can be repositioned to accomodate some slack, but you may not have that option.
you can get the cables from your bmw dealer or other sources like Motobins- I'd at least look at the fiches at MAX BMW or Bob's BMW, or A&S Cycles to see the part numbers/options - I haven't ordered anything from the website you indicate, so I can't offer any advice on them specifically.