angle grinder: The gear ratio is probably around 4:1 or more so you’d either be turning the knob forever or it would be very difficult to turn
Wood gears: Much harder than you think, but not impossible with the right tools, but I’m assuming you don’t have them. If you are determined you can go check out woodgears.ca however, he has some templates you can print out and cut out.
Bicycle cassette: Those are sprockets not gears. They would be quite clunky and difficult to use as gears.
The best thing to do would be to simply relocate the valve. With some sharkbite fittings and some copper pipe and a Pipe Cutter you could easily relocate the valve, and there would be less work than trying to fit in a cobbled together right angle gearbox.