You should shorten the linkage. You also will need to verify the proper function of the linkage due to your unknown combination. The linkages should have a slip joint in it somewhere. As the throttle linkage moves you should get significant movement of the transmission rod before any inj pump movement takes place. I don't think just a link adjustment will be enough, I presume you are not getting that pre-power linkage movement.
Bosch Master, ASE Master, L1
33 years MB technician