I use 3F for both my flintlock and percussion .50 rifles, and .62 flintlock smoothbore fowler. My standard big game load for both is 70 grains of 3F. I prime with 3F also, all from the same horn.
I think 120 grains is excessive in a round ball gun, unless you're going after grissly bear at close range.
I have a black powder, .450 Express dating to around 1900, that takes 120 grains of 2F and fires a 480 grain conical bullet. At one time this was a popular round for dangerous game in Africa, things such as lion, rhino, and cape buffalo. It was also a very popular round for European stags and wild boar.
A smoothbore load for small game is something that you will have to work out with your individual fusil. I can tell you that squirrels have a tough hide. I use nothing less than #6 shot for them. In fact, I like #6 for just about all small, upland game, and would put #4 shot at the upper limit for most small game. For turkeys I will use #6, 5, or 4; whatever I have on hand. Head shots only.
I do drop down to #7 1/2 shot for doves and woodcock, but don't consider it adequate for anything larger.
#9, in my opinion, is only suitable for clay birds or shooting mice at close range.
When I lived up north I used to train bird dogs. I needed a lot of live pigeons. I would go to a grain elevator where hundreds of pigeons hung out, feeding on spilled grain. I used a cannon net with four homemade cannons to pull the net over the birds. Iron tubes with car pistons for cannon balls were used. A charge of 140 grains of 2F in each of the 4 cannons was fired electrically so they went off simultaneously. The system worked well for collecting several hundred live pigeons all at once.