According to
Peter Kohler, the 1950 Raleigh Clubman had 71° seat and 73° head angles (the two year's previous models were more slack). My '73 Raleigh SuperCourse, which I've built up as a Clubman-style bike with 5-speed IGH and drop bars has 73° parallel angles:
An early 70s SuperCourse is a great platform for this concept, given the stamped dropouts without a derailleur hanger and that they're plentiful and can usually be had for pretty small money. I've had a '50 and '51 Raleigh Clubman (currently have a '49), and the SuperCourse has a very similar ride.