I believe the housing of the pumps used in both the system shown on the SIA pic and Branson car is designed like a "wye" in plumbing. The pump drops into the block in place of the distributor, and is driven off the cam. The distributor then drops into an opening along the RH side of the pump housing and is driven off the pump. I suspect that, in such small space, the driving force is transmitted entirely through a geared connection.

Since timing of the squirt of fuel is just as critical as the spark of ignition, I have to wonder if Packard abandoned the front-mounted pump driven by a cog belt (off the crank pulley) in favor of this system, which might have offered greater precison/reliability of timing due to the use of gears.

BTW, after finding out who owned the car with the FI system shown at Branson, I would now say that the system on that car is the original prototype system reinstalled, but with some substitute parts and minor modifications. It's a pity that they couldn't fix and use the original pump.