I'm guessing the one you're modifying is the 1946 Raleigh you've mentioned in your sig as 'plan to modernize', if that was the original plan, by all means continue.
The 1949 is mentioned as been planned to 'keep original'. If you plan on making a similar upgrade to drum brakes to the '49 Raleigh, then the AB3 and the BF will be period appropriate (as previously mentioned, similar to a factory upgrade of that period), they'll drop right into the bike with minimal modification to the hubs.
These new hubs are all 36 hole drilling, in contrast to the 32/40 hole drilling of the old Sturmey Archer hubs. Steel or Aluminium Raleigh pattern rims (on the theory of keeping as original appearance as possible) in the 36h drilling for 26 x 1 3/8 are either going to be an ebay.uk hunt or a hunt through Dutch bicycle shops. In Europe, I believe that Rigida makes these rims, mostly for the Dutch market.