I've an Optima 4x,40mm that I bought from an antiques centre (Lots of stalls with different owners!), Think it was £25 but with no mounts..

Pic 1

I put it on a 1979 HW35, The 35 action is now in a Luxus stock that I bought from IJ at one of the Melbourne fayres

Pic 2

Pic 3


John