Look for a PM with my contact info, I can send you a BSA Factory workshop manual as well as the factory parts book. (The parts book is invaluable and inconceivable to take on a job without one.........Lets see here, I forgot! Which way does the wigglestick fit against the wazzledis, and where does the locktab go?)
I will ask about file sharing here, but there is a variety of websites that shop manuals and parts books can be downloaded for free,,
BSA had a weird way of doing most everything. I am sure many decisions were besotted gin fueled ideas, but much of it is Pendantic engineers and organizing things only an engineer would do. (With a touch of OCD). So, for much of the history of early BSA they had a bewildering way of communication and Triumph would print a parts book for every year and model and then they came out with a workshop manual every few years with updates and tailored to the newer models.
BSA did not start doing this until late 50s and more so in the 1960s when of course BSA &Triumph had merged. But the early models the "Manuals" tend to more like a owners manual, and less a workshop manual. (At least much of the material I read, but not all of them certainly). But they did make great use out of the "Service sheets". I dont know how accessible these service sheets were to the regular owners, but they are similar to factory service bulletins other makes and models used. But they cover all the models from M models, A, B, C and things like Bantams. They are numbered 200 series, 300 series etc etc and they added and subtracted these infilled over the years. I have several versions of these and a master copy is around 1250 pages with a lot of the material NOT related to your specific model.
Here is a sample from the 800 series...:
808 1960 A, B, M C10 & C11 Wiring diagram (negative earth) 2
808 1965 A, B, M C10 & C11 Wiring diagram (negative earth) 2
808A A, B & M group Wiring diagram (positive earth) 2
808A 1954 A, B & M group Wiring diagram (positive earth) 2
808A 1961 A, B & M group Wiring diagram (positive earth) 2
808C 1958 C10L (54 -55) and C11G Wiring diagram 2
808D 1961 C12 and C10L Wiring diagram 2
808F 1957 M group, 56-57,B group, 55-57 Wiring diagram (positive earth) 2
808F 1958 M group, 56-57,B group, 55-57 Wiring diagram (positive earth) 2
808H 1959 B group fitted with alternator Wiring diagram (positive earth) 1
808J C15 and B40 Wiring diagram 2
809 All, except alternator models Generators model E3H and E3HM 8
809 1948 All, except alternator models Generators model E3H and E3HM
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So, may i suggest literature and service data is job #1
#2, compile a list of parts that are useable and can be serviced and rebuilt
#3, Compile a list of parts needed and begin acquisition