Well, I was able to handle/see the pistol. There are, indeed, NO manufacturer marks on it anywhere. The grips are not ivory. Once removing the grips, it was easily evident that they were wood based on the unfinished side.
The rear sight is actually a peep sight. The front sight has been removed, likely not intentionally.
It is indeed a 22LR, but the cylinder is unusually long for that load.
There was an unused threaded plug about 2/3rds of the way down the barrel, which probably was where a shell extractor could have been mounted, but the revolver frame doesn't appear to be designed for it ever having an extractor.
Thank you for the suggestion of trying to determine SAE or metric screws. I'll see if I can get that info. I actually do have the pistol temporarily in my possession.
Thanks to all for the input.