From his headstone I have a birthdate of October 23, 1849. since Walthall was formed from parts of Marion and Pike, so it is possible he could have been in Pike Co. I suppose he could have served in a homeguard unit at some point in time and maybe his father served in one of the Marion Co. units. If so I will need those records.
I have found transcriptions online is that what you have? If you have hard copies, would it be possible to look up John G. Purvis and see if his wife's full name is listed? This is my gg-grandfather who served in Co. D of the 7th. I believe his first wife and child died during the WBTS.