These are clunky gears...on upshift preload the shifter a bit (upward pressure) and as you clutch it, go firm and fast.
They are big, square-cut gears.
I idle mine at 1000...just so my alternator will supply full load for my lights and the cooling fan on the rare occasions I get stuck in traffic.
I don't idle much

If you want to bring it down the adjustment is a thumb screw between the carbs on the right side. I think the spec is 800-1000 but I don't actually recall.
Also possible there are vacuum leaks causing it...check the vacuum lines, particularly where they attach to the manifolds...and ya may want to do a vacuum test on your petcock.