We normally saw about 5-7 HP increase from the same engine updraft vs. Horizontal draft, in the test cell. In addition, the 360 with the forward facing sump and 9:1 pistons pretty much put out 192-193 HP at full power with standard mag ignition and EI that held the timing to 25 BTDC for TO. I would assume, you would see similar gains on the 320 from the stock 160HP configuration.
"The opinions and information provided in this and all of my posts are hopefully helpful to you. Please use the information provided responsibly and at your own risk."