I too recently explored these paths to 'finder guiders' the concept is a good one,I like the fact they are light.
I have no experience in making such mods,But explored many options.Very recently I made my decision to buy a 50 mm Borg guide scope with Borg brackets,see this link
http://www.sciencecenter.net/hutech/...opes/index.htm
The one to get is the AG50B2B this works with orion or QHY5 guiders.
The brackets are no 7060.
I did seriously think of buying a cheap finder and paying someone to mod it,but by the time I paid all that,I would have been half way to the Borg cost wise,so may as well just buy the Borg straight up.
A little pricy- $319 scope,$79 for brackets and $44 USPS,but well worth it-looks good with the new Vixen GPD2 and 103 refractor,Also I had some concerns with modded 'finder guider' in regards to flex issues,only 3 screws holding scope a guide camera.Also the Borg has a focuser.
Hope this helps-good luck.Chris