I've had the idea to try a PT2399 chorus ever since I modded my Clari into a Clari Cubed. The challenge with the PT2399 is to get the delay time as short as possible while still having some wiggle room for the LFO injected into pin 6. I've tried PNP, NPN, FET and LDR - fail! The delay time is either too short for the LFO to have any wiggle, or too long and latency is obvious.
So, screw using pin 6, just ground the MF for the shortest possible delay time and instead modulate the vref at pin2. Shortest possible delay with as much LFO wiggle as you want. In fact it has to be tamed down or you're into tape wobble type effects.
Those familiar with the PT2399 family of delays will recognise homage to Rebote and the Clari in the input buffer and output section respectively.