9300 isn't bad its what I have been seeing on my 1st bench runs of the 120 with a 15/6 prop.
after checking that carb/intake O ring to see if its hard or has a flattened side at the manifold my gasket looked OK in the carb body, but when I really looked at it after popping it out of the body there was a definite flat spot on the inside and the rubber was really stiff and felt old compared to the new one, I could tell there was a loose seal when the engine was running it wasn't smooth and consistent like yours,also the carb was pretty loose like it just slid onto the manifold with little to no effort after installing the new gasket it took a little work to get the carb on I am sure that was part of my erratic tuning.
on a more positive note on my other 120 with the pump, after resetting the screw on the back of the pump to match the one I have that had not been messed with, and installing the bearings, crank, piston, and pump, I got the pump to push fuel at a reasonable rate I still don't have accurate pressure numbers to work from but I am confident the engine will run, it's mostly assembled now I just need to go through the carb and adjust the valves, then I can get some runs in and see how she goes.
there is also a article from one of the engine guru's, Clarence Lee, about plumbing the fuel lines to reduce the pressure to the carb on these older pumpers to the return line so they don't get all floody and over fueled,at least I got the pump to move fuel thats a step once these old fuel pumps go bad there just parts engines.