Matt,
Your Dunhill Bruyere was made in 1967 and is a Group 4 bowl, the A signifies it is a Bruyere finish, I believe the 1 has something to do with either the sale date or if it were sent back to Dunhill for a warranty item but not totally certain on that, I have no help,for you on the 290 shape designation except it’s a Billiard and a beautiful pipe. I hope in some way this answers a little bit of your pipes information, regards.
banjo