I've just enjoyed going through this thread – one of the classiest Raleigh models I've seen, I must say, and great attention to detail on the build.
Going back to the question of the 20c tyres, I was a bit apprehensive myself when I had to go skinny (also Dynamic Classics) due to some very tight clearances on a frame. They've turned out to be totally fine, and I can't notice any difference with the 23c ones on a different steel bike in terms of how they feel on the road. Obviously it depends on a few factors like the rider/tyre pressure, etc, but I suspect on a well made bike from the right era, it shouldn't be an issue. After-all, it was fairly standard back in the day...
