Lovely to see you restoring this lovely bike.
Bought one of these new, with the money I got from my paper round when I was 13/14 ish, and cycled around on it for years, finally parting company with it in 2006, when I emigrated to Sweden.
If memory serves it originally had a 14-24 freewheel.
I changed the original mech for a Shimano, and bar-end shifters, and swapped the 49T for a 44T, and then converted it to 10-Speed with a 52/40 (cotterless, which I don't remember being too much), not an ideal combo, since it meant a lot of duplication, so only 7 different ratios in reality, a 14-28 would have been better.
Interesting you paid £50 for the frame and fork, as I think that is what I paid for the bike originally