ESCCO did a white sapphire cantilever/Paratrace stylus mod on a Zu Denon 103R, which is a giant slayer as far as I'm concerned.
There's also Andy's Needle Clinic in the Seattle area, although I have no experience with him. I hear the turn-around with Andy's is quicker than most, but be prepared for a good 3-4 month turn-around with either SS or ESCCO.
Best,
Dan