I bought my B31 early in 2022 and spent most of this year stripping it down and rebuilding it, full story on my YouTube channel https://www.youtube.com/c/InTheShedUK
I have had the D1 for years, in bits in the shed, but during lockdown I decided to use the time to put it back together (engine had already been rebuilt some time ago), I painted it red as it was what I had laying around in the shed and I used to be a postie so seemed apt!
Unfortunately I did not video the rebuild but there are a couple of videos on my channel when I fitted Electronic Ignition.
A few pics: B31 before & after, D1