Hello Doug / Tony,Tony
I think the only assistance I can provide is that the drawing that accompanies that pack from Slaters shows it as being a shoc Open wagon from the springs on the sole bar (I think also that BR open wagons had diagonal frame members whereas vans where all square). On Bartlett there are a number of shoc opens that have ‘Morton-style’ long hand brake levers without lifting links, such as this one.
BR 12t 5 plank shock open merchandise wagon OSV ZGV | B721357 SHOC-BAR @ Hitchin engineers 75-08-10 © Paul Bartlett w
So I think this pack is correct for converting a shoc open wagon to 8 shoe brake without lifting links, but not necessarily for other BR wagons...
Doug