Had a little play around with my lathe this arvo.
This is what I came up with.
Piezo is a momentary 16x1mm thread.
The bright end at this stage is a 3x XML DX drop in but that may change. Perhaps the 5 or 6 XR-E version???
Perhaps a 44mm aspheric and single XML but that would mean re machining the rear end to make it a little longer.