You are lucky - I've been trying to find one with a split counterweight for ages.
If I had one, I would actually interchange the part which carries the weigh rod with the larger part. I would position the smaller part (carrying the weigh rod) right up against the bearing block, with the transverse distance of the weigh rod/playing weight adjusted to provide equal loading of the knife-edge bearings (as described in the setting up instructions). Then move the playing weight so that the main part of it is in line with knife edge bearings (i.e. in line with the chrome screws of the bearing housing). Now move the larger part of the counterweight so that the arm and cartridge is balanced. Then using a set of stylus scales move the main counterweight forward so the correct VTF is achieved. In doing so, the arm will have been set up so that it has minimum effective mass.