BGM Clubman Fitting Issues

I have a series 3 LI150, with a BGM RT195 kit fitted. Have run this kit with a 42mm AF Clubman and a Sterling Expansion Pipe. I have just purchased and fitted a BGM Clubman. Last job of the fitting was to reinstall the rear shock after having tilted engine down to remove the cowl etc. When i lift the back end of the frame up, the exhaust is touching the underside of the scooter before the mounts are far enough apart to install the rear shock. taking some measurements, it looks like i had a series 2 shock (310mm eye to eye length) instead of a series 3 shock (300mm). I can just achieve 300mm on the mounts before the exhaust touches the underside.
Assuming i purchase and fit a series 3 shock, is this still too tight underneath, how much will the shock compress with just the weight of the scooter? Obviously will compress further when i sit on it.
Assuming i purchase and fit a series 3 shock, is this still too tight underneath, how much will the shock compress with just the weight of the scooter? Obviously will compress further when i sit on it.