That is a nice project.
Give it a good wipeover, clean, and wax and polish, you may be surprised at how well it will come up.
Original paint and finish bikes are highly prized these days.
If that were mine, I wouldn't alter anything.
It will get a lot of attention.
They are only original ONCE !
It is later than the wedge tank models, and still has the maggie in front of the engine.
That makes it later 1920s.
Its a sidevalve single (obviously).
What does the other side look like - something like this (not the right muffler) this a 1928 M1 500cc
Raleigh of Nottingham made their own motorcycles and engines, and also sold them (engines) under the 'Sturmey Archer' brand.
Gearboxes also, many a maker used their gearboxes.