Interesting thread (pun intended!
).
Sorry I can't offer much, but I hope you'll let us know how you get on on this little project. It sounds interesting.
I bought my old 8"Newt second hand from an elderly gentleman in St Ives in Sydney about 25 years ago. Amongst the stuff that was in it was a home made reticle. From memory it was two crossed wires (very fine) soldered into a ring made from brass shim. It slid up the inside of the eyepiece - the threaded bit where the filters screw in. I remember being impressed with his fitting skills, but I can't remember how it stayed there now...
Time has dimmed the memory...
Al.