I want to put new tile over my existing tile in a standup shower. I have owned this home for 20 yrs and I know the waterproofing and pan are not leaking. I do plan on installing new waterproofing over the tile by means of a properly adhered fluid applied material or sheet good waterproofing like Bituthene. Sloping to the drain isn't an issue and I plan on epoxy setting a new drain inside the old brass one. Does this sound acceptable?