I'm sorry if this has been covered, a quick search didn't yield much. There was a recent post about a seller on Etsy selling lens boards that are set up for M42/L39 lenses. Any advice on this would be appreciated, I'd like to hear from someone with more experience than me (literally everyone on this forum) before I purchase.

I know there are many things to consider, like my lens cap would be the shutter. Another one is focus. Would you set the lens to infinity then focus w/gg? Will this work at all??? One of the lenses I'd like to try is a Soviet Helios w/the front element reversed. This will most likely make focusing even more difficult due to the very small "focus" area on the reversed lens, and how much (or how little) coverage I get.
Thank you.
Michael