Gen 2 Rear Shock advice please


Looking for advice on starting with a stock rear shock on a 12" extended / lowered swing arm with 190 Shinko. Stock motor with Muzzy 4-2-1 and PC 3. Rider weight 215 pounds in track gear. There are a lot of options available for after market shocks and several companies who will sell springs and new valve services. WouLd like to Test & Tune a little before the winter sets in and a starting point on the stock shock would be appreciated. I recognize the stock shock is not optimal, but would like to start with this and get a feel for what I need.