I am mounting faucets in my tub deck and will need to drill holes: 2 are 1 3/8" and 2 are 1 1/2". I notice they sell 1 3/8 carbide tipped hole saws. I assume the carbide will cut through marble tile. Any suggestions about the 1 1/2" hole? I can't seem to locate anything locally. I'd thought of using the hole saw then enlarging the hole with a diamond rod saw. Any thoughts?