Parallax was/is corrected for by a cam that raises/lowers the upper lens to compensate. I don't remember if it had infinity focus as we only used them for portraiture. John can probably answer the infinity question.
If I remember correctly, the Keith "factory" was in Riverside, California. As we were in Ontario, CA it made repairs etc. very convenient.
The lenses were matched pretty closely as the focus always seemed accurate. Although we always shot stopped down pretty far.
Anyone out there remember the McVan TLR? Frank? I used to use one of those with a split 5x7 back for b&w portraits.