There were photos of the K100 front end bring fitted, but I am not sure that they would tell you anything.
I will set out a few pointers though
The good news is that as far as the mechanical aspects go, fitting the K100 front end is a bolt on, same head stem bearings, same stem height - it is easy.
But, like all things there are complications to be aware of.
Firstly, if at all possible buy a complete K100 front end, in fact if at all possible remove the front end from the donor bike yourself. The reason for this is that the little bits you don't get will cost a fortune to buy individually on the 2nd hand market.
To that end you want the forks, triple clamps, handle bar mounts, brake fluid tube that goes down the centre of the steering stem.
Mudguard and mounts, calipers and hose mounts, front wheels axle and spacers.
The front "plate" from the R65 that mounts the lights and instruments needs to be cut at the bottom, the plate can be mounted usuinng bolt holes already in the K100 triple clamps but you will need to make your own spacers.
For brake lines I bought a braided stainless steel set that Motobins had on special - now I would buy Venhill.
Ok, now you still have a few decisions to make, the first being ride height. The K100 forks are both longer and have longer travel than the OEM R65 units. I decided to have approximately 1.5" of fork leg protruding above the top triple clamp as anything more looked a bit strange.
However my R65 is now bit taller in the front end which meant I had to buy an r100 centre and side stand. The centre stand was a significant cost. In retrospect I should have paid a local engineering works to make the centre stand 1" taller and fitted a block to the bottom of the side stand.
Servicing the K100 forks is easy, they are really just overgrown R65 forks, or at least the very early ones I bought (complete with Brembo casting mark) were was.
BMW thought the front end of the early K100 was stiff enough to not require a brace - they were deluded, a brace is essential for enthusiastic riding.
You can still buy a Tarozzi brace, these are the gold standard but like anything made in Italy you will need a sharp mill file to adjust the fit.
Ignore anyone who bleats about altered geometry, they do not know what they are talking about. The K100 forks are of centre axle design and the triple trees are not offset.
Tyre wise I run Pirelli sport demons - 100/90-18 front and 110/90-18 rear. I love the handling.
There is probably more, ask me anything.
Your 4-spot calipers will bolt on and paired with a 14-16mm master cylinder will offer powerful breaking (I would fit a 14mm one which tells you how I like my brakes, my twin piston K100 brakes are run by the original 12mm master cylinder, it does good stoppies!