There's a v spring update (years ago) with yellow paint on the ends that can help
Also, if your shift interrupt switch is the older style, spring arm/roller style the adjustment is a #1 phillips and needle nose
16in at idle is good, yes. Needs to be steady, like less than +/- 1in for minutes
If fuel pressure under load is okay with a vacuum drop continously until wot with steady you're good, for now
Guessing it's the tree clip speedo tube clamp attached to the forward side of the exhaust passage at the bell housing?
If so, no worries. Speedo tube is independent of any water passage save for the pitot at the leading edge of the gearcase
I'm thinking the excess is exactly this. Overflow/spill tube from fuel pump is dumping excess fuel from a ruptured diaphragm into the carb
OP has mistaken the air horn inlet/tygon hose for the bowl vent?
