I would like to put a riser block on the handlebars of my '01 MXZ 600. Can I go 2" with the stock cables and wires?

I've heard that 2 inches is the most you can go without changing the cables. You should be ok.

I had a 2" on mine with no problems but went back to a 1". I liked it better. My buddy tried a 3" and it was too much.

2 inches.

Would that be the same for a 99 mxz? in the S2000

Yes 2" on a s-2000 is fine.