Yes, an improvement upon the comparable drawing in GWSG "S&C Practice", good to see the table of "variations" in the RF-RF distance for different switch lengths. What is missing from this drawing (and from the quoted reference book) is the angle of divergence between the switch and stock rails.
The reason for asking for GWR drawings is that 3D printed chairs have a disadvantage when compared to the ABS mouldings that are supplied by the S7 Group... the 3D chairs are rigid and inflexible whereas a 1S chair made by cutting ABS chairs is both flexible (to an extent) and can be "adjusted" to fit the model turnout. If a 1S chair made as a 3D print derived from the drawings in the S&C Practice book, or the illustration above, then there is a good chance that either the chair is going to fracture when used or the Switch rail is not going to lie close to the Stock rail along the planed section (and yes, both of those statements reflect recent
occurences in using 3D 1S and 2S chairs).
Looks like a trip to Didcot to hunt for suitable research material, preferably in a stack/pile of fittings rather than incorporated into a turnout along the main ladder.
regards, Graham