The best and most accurate and complete source for regimental strength of the Army of Tennessee or the Army of Northern Virginia in the second half 1864 will be Confederate inspection reports. These also include arms used by each regiment in nearly all units. You are already familiar with this source. For others who are not, it's not on line anywhere, but is available in microfilm from the National Archives. This is M935, Inspection Reports and Related Records Received by the Inspection Branch in the Confederate Adjutant and Inspector General's Office, eighteen reels of film.