Blew my upper gearset in my B1 1.50 ratio drive. In a desperate attempt to salvage my vacation I found a B2 1.65 upper..

Now.. everything I can find, suggests that the B1 1.5 upper and the B2 1.65 upper are the same. Both have the same 32/27 gearset, and only the lower gearset in the B2 makes up the difference to the 1.65 ratio. Part numbers also confirm this.

Reaching out in the hopes someone can add some validity to this.. Is it correct?

Yes that is accurate