Interesting. Did the original owner say they bought it this way new or is there a chance they swapped out the bow ties for imperials later on?
Ludwig was notorious for this type of thing. Different badges, different lugs, etc. When they ran out of bowties, they'd use imperials. Shells were the same way as there are 10 lug Acrolites and 8 lug Supras. Badges were grabbed out of sevral different boxes so kits had both keystone and B/O badges.
Then there were the special order drums. I own a 1976 6.5 Acrolite with factory imperials. Try and find a 1976 6.5 acro......with bowties. One has never been seen or documented.