I am not sure if this is the correct red, but I believe it is a colour equivalent for one of the BSA reds.
'Vauxhall 230S'
You could contact Brian 'Polly' Palmer at Bri Tie Motorcycles, as I think he sells paint for BSA's and can probably be a lot more help.
Bri-Tie Motorcycles
Cwmsannan House
Llanfynydd, Carmarthen, Dyfed.
SA32 7TQ
Telephone 01558-668579
Great-Britain