Those census sheets show that someone in the family provided the birthdates/ages from memory.We have no idea whom which does cause some problems since each census is not on the same date.
You are on the right track compiling the marriages, births, and deaths which will either add or detract from those ages listed in the census.
Looks like searches into the court as well as the church records will add more data to narrow those dates in the census.
That was a gem you discovered in that book about Mason Co. You just never know what you will uncover in old published works of histories and families.
I would continue looking for wills and administrations, appraisals and bonds, petit and grand jury lists, voting lists, school lists, fraternal organizations, militia and military lists, grange lists, diaries by doctors, preachers, druggists, grocers, hardware, etc.You can be suprised at what you do uncover in the records.