If you're referring to the central supercharger that runs on a vertical axis. Like the picture above of the 1937 Supercharged Graham. They had a drive shaft that ran straight down vertically, into a gearbox with a 90* bevel drive. That ran an a short shaft out the front that was then belt driven from the crankshaft/harmonic balancer. One of the pictures above show it. The gear box is mounted forward of the starter motor and the driver pulley in mounted below the generator.
You've got me thinking about these systems now too. I really like these old set ups. But would be almost impossible to find one today. Have been thinking about using a little toyota roots type supercharger and do a blow through on a triple carb manifold I already have. The centrifugal units above all seem to give about 20-30 hp boost in power, but these are factory spec engines and were covered by factory warranty. So I'm guessing with modern fuels, oils, pistons and modified oil systems ,you could safely double these figures. 110hp stock up to 150-170hp. That'd be a worth while gain and send and old Chrysler flat head flying down the highway. It just takes time and money.....