Don't do that. You will be under driving the water pump and that is bad.
Also, not sure about that 3 groove lower pulley but I've never seen on that can be balanced and someone was drilling on that thing. I set that aside and try something different.
FWIW there are now several companies making pulleys that are relatively inexpensive and you can get pretty much what you want.
Whatever you do, the water pump pulley MUST be smaller than the crank pulley. An absolute must if you want a cooling system to do its job.
Correctly sized radiator.
Good high volume water pump.
Quality high flow thermostat (Stewart Components).
Water pump turning at least 5% over and 10% is much better.
You do that and you'll keep your engine cool in the bowels of hell.
