BSA made this easy for S/A owners. The crankcases are marked F and R, so look closely and the remains of the stamping may be just visible. Suss out the oiltank connections and join up the pipes, Feed pipe from the internal tank filter is the lower connection on the back of the tank. Return is the longer, upper connection, with provision for the banjo feed T to the rockers.
Plunger models have a fixed bolt on connection to the crankcase. Here the pipes line up perfectly* with their respective connections to the oiltank .....
Swarfy.
* Totally unbiased comment to demonstrate the superior qualities of the Plunge design.
Additional. Bergs may like to add further practical comment. CB said it far more simply and was just a bit quicker to the keyboard. Also here with a new Avatar (which I have not seen before) extolling certain aspects of current activity. Nice one!