I need to make or buy a mechanism to allow the single handle throttle on my 1971 Donzi 18' with the Volvo drive to shift into gear before the throttle raises the RPMs. Can anyone show a mechanism that will allow the throttle cable to start moving the actual carberetor linkage after the shifter has engaged the drive? It looks like it needs to give at least about 1/2" before activating the carburetor linkage - correct? Bill