I help John Underhill with the Scott Machine Register and have the details on my PC. The Frame No and Engine No you quote could well be the original pairing and date about the 2nd quarter of 1926. Originally this would have been fitted with 26 x 3 beaded edge tyres. If you have the long petrol tank then the model is possibly a 2 Speed Flying Squirrel. I would need to see a photo to confirm this. The Scott despatch records are held in the VMCC library and it should be possible to discover the original specification of the bike and to whom it was despatched. I once had a 1926 2 Speeder Frame No 1922.
I set up my 2 speed gear so that one needs to hold it in the Low position to keep driving. The High gear position should be adjusted so the clamp holds it in drive. Full details of adjustment are given in The Book of the Scott. The large rear sprocket should have 66 teeth if it is on solo gearing.