Can you not pass up a chip shop or a burger joint???

If you are under 160lbs, I'd say get a SE/SP shock and install a Race-Tech gold valve along with a rebuild. I have one and it works great.

If over, keep looking for Ohlins/Penske/Fox shock with ride height adjustability. However, If you have aftermarket pipes, you'll be limited on how much you can raise the rear end on the MC21. With minimal machining work (drill press and a bench grinder), you could make a CBR600F2/F3 aftermarket shock fit. The stock Showa shock won't do you much good as it is a few mm shorter. I have been using a F2 Fox shock on my racing MC28 for a few years.