David beat me to it, I have done the same on two previous Sevens, one a live axle and the other DD, both of which I used for autotesting back in the day. For the first one I used a Morgan flyoff, which was great but it was heavy as hell, and the second, like David, I used an MG Midget, and taped the button down. They fit on the passenger side, just in front of the gearlever, and bolt onto chassis members, both longitudenal and the cross mount, the cable is then shortened to fit, works a treat. The point is, it doesn't have to be fitted on top of the tunnel, where it can get in the way of your elbow and is harder to get at for that bit of tailout action.