A while ago converted a rescued Raleigh Sprite 27 to 700C with Shimano Nexus 8 speed IGH and dynamo front hub. After using it to tow a trailer, a couple problems came up.

The original Nervar 52 tooth chainring was just too big. Needed something smaller. I found a new Stronglight single that would do the job. Only issue was that I needed to convert to modern JIS taper.

Photos show facing BB shell down to 68 mm from 71 mm and re-tapping with Raleigh the 26 TPI threads. The bottom bracket was fitted with Phil Wood 26 TPI Raleigh Super Corsa cups, chain line set, and crankset was installed for last time. Works great now.

There have been some posts here discussing the use of Shimano UN-72 BB with the Phil Wood cups. have not tried, but IMO, they should work.