Little update here:
15k miles after installing a SMF with Fluidampr and I've lost 2nd gear synchro. Not totally surprised, but not happy to have to dive back into the transmission. I'll be adding the 4th gear support brace this time around, AND have sourced some 02M brass synchros from Darkside to try and fit. The part number for the 1-2 synchro hub is compatible in ETKA from 02Q and 02M, so my hope is that the synchro sets are interchangeable. The synchro hub for 3-4 is not exact (part number has different ending letter), but ordered them just to see.
I also over the past 5k miles have developed a knocking sound that is wheel speed dependent, and only seems to happen when decelerating in gears 1-4. Noise goes away once you apply the slightest bit of fuel. It doesn't sound like bearing noise because it's not a hum, and it doesn't change frequency when shifting weight from side to side. Hopefully opening the gearbox again will shed some light on things, but I'm hoping it's something easy. This later 02Q does not have compensation washers on the input shaft bearing like previous 02M and early 02Qs, so I don't feel that's the issue however it is a similar symptom from the searching I've done.