It is also a good opportunity for anyone who wants to experience an Asian 660 with the Cross P+C to run one. Neither of these saws has any additional port work, and the only replacement parts (from the kit) are OEM piston pin bearings and piston pin clips.
They both were assembled w/o a base gasket, with .020 timing advance, and muff mods. Twin #1 has a 1/2 hole through the back of the baffle, Twin #2 has the baffle essentially removed, and more aggressive venting than #1.
IMO, they run a good deal stronger than a stock (or similarly modded) 066/660.