Nice looking Flash, Frank!
Messrs. Amal are correct. But you're not in this for concours (as evidenced by your TLS front brake), so why are you concerned? True, the 376 choke is 1/8th-inch smaller than the 389 choke, but I doubt this will affect performance in a noticeable way.
Bear in mind that the number following the slant is a "build" number that has no importance to the user.
As for differences in the two engines, I suppose the inlet tracts are different to match the chokes; I can't comment on other differences.