Got a 1994 CBR600 shock, $28 shipped, it's nearly identical to MC18 secs, I was using Ohlins specs as a reference, only issue is that CBR has a smaller hole on the top mount and it's too wide, but that's an easy thing to correct, drill the bushing and shave the sides.
Reason I went with '94 is that it was the first year they had remote reservoir and full adjustment, compression and rebound. Spring rate is 50 lbs more than MC21 (I assume MC18 has similar rate?)
Once its rebuilt and modified I will update further. I don't expect a miracle but at low budget solution.
Also I had 6 sets of HRC linkage plates made, will try with it with stock and HRC spec plates.