That style of carb on the briggs is really bad to get either corrosion or debris in the idle circuit of the carb which is the cause for surging. The down side of that carb is because of the hidden passages, no amount of cleaning will get it to run correctly in some cases and your only option is to replace the carb.
At last track the carb did cost much more than installing the repair kit plus your time.
That is the reason that a lot of repair shops have gone to just replacing the carbs on equipment, instead of cleaning and installing kits, because with a lot of the new carbs you have a 50/50 chance of getting is to work properly after carb repair. If it doesn't run correctly the shop has wasted the repair kit, the technicians time, and shop money.