An interesting project. A couple of points:
The Chater B.B. needs 5/16th balls. I expect you know this, but not everyone does.
As I've mentioned elsewhere, I have used 3/32nd chain rings with an 1/8th chain and this caused no problem.
That block looks like 16 - 22 teeth, so a 48 inner with 26" wheels will give a bottom gear of 56.7" - quite high by modern standards.
Looking at the photo of the rear mech in post no. 6, it's worth bearing in mind that the nut on the end of the telescopic shaft (next to "4 vit.") is difficult to tighten since it's hard to hold the shaft. If it comes adrift in use the results are undesirable!
Chroming: If you do have this done, make sure the area to be chromed is not shotblasted first - it is almost impossible to polish out the effect of the blasting.
Good luck with this - I hope you get to ride many miles on the finished job.