This looks very promising. The estimate of his birth year as 1868 was based largely on census records citations, which are themselves estimates in most cases. November of '67 is certainly within that ballpark, and looks to be the correct person, especially if you did a good search and found no other likely candidates. With being the one doing the search, I am more than confident that you "did a good one." Your devotion to task is most admirable, for which I am extremely grateful and indebted to you. I will definitely use that date as his assumed birth date in my genealogy, citing your help, of course.
I may eventually want to get a copy of that record, but my question to you is how you found its contents. How do you know, and where did you access what it says, since you obviously didn't purchase a certified copy? Simply citing whatever that source is, might be sufficient for my purposes, too, especially since I already know much of what is offered there, and would only be confirming that this is, indeed, the correct person and the correct birth date for him (if all the pertinent information is even there).
If at some point I am able to shake loose some continued lineage for Sol/Frank, I will probably want to firmly establish his birth date. Short of that lineage, however, I may forgo the formality of that confirmation. That's okay, since there are plenty of other folks to research. You can't nail 'em all, even with the help of wonderfully devoted and highly talented and experienced researchers such as yourself. I really can't thank you enough for all your help with this. You're very special. With your commitment I can only imagine how developed your own genealogy must be.