I am considering having it upgraded by the Needle Doctor, to the sapphire boron with nude micro ridge stylus.
Sapphire or Boron, not all together
What's the price and why do you think it will be better than another cartridge (not a refurbished one, but a factory made) with similar advanced cantilever and stylus ?
You have to ask about compliance of the new combo.
Actually what Needle Doctor offering for Denon can be purchased for many vintage MM cartridges, because modern
JICO SAS stylus is sapphire (or ruby) with S.A.S. profile. And a broken cartridges body like Victor Z1 cost almost nothing (fully compatible with JICO SAS stylus).
Denon is LOMC and you need a SUT of high gain MC phono stage, also proper phono cable.