I had one of those, as a runabout.
46 cubic inch side valve v-twin.
The throttle and front brake lever were in the usual place. There was a twist grip on the left handlebar too, which operated ignition advance/retard. No handlebar lever on the left though, as the clutch was operated by the right foot, a heel and toe affair which could be placed in any position without springing into the engaged position. It meant that you could take your foot off and place it on the ground whilst the thing was in gear. It also helped in muddy going as you could put the clutch into a slipping mode whilst paddling with both legs.
Gear change was hand operated lever in a simple 3 speed gate on the side of the tank.
Sounds like a WLA/WLC 45 (45 cubic inch/750cc) wartime model.
It was seeing European bikes with foot gearchange and handlebar clutch which brought HD into our modern ways.
Imagine braking hard into a downhill curve with the HD 'suicide clutch' - shutting throttle whilst using front brake with one hand, changing down with tank mounted gearchange with the other whilst pressing down on foot clutch and foot brake!