Without knowing any trumpeters in particular beginning with "Z", yeah a 1503 must be it, being Kanstul's "72LT clone".
So I take it the Plaza is not a straight up copy of any Kanstul? The name makes me think of the Kanstul Coliseum but the specs don't match up.
[Edited once I realized I was mixing horns]
The Plaza uses a more orchestral bell than that, and it is on a Kanstul-made mandrel. The Coliseum bell is faster taper than even the 72, this bell is less so. BAC is not building a horn with the Coliseum bell yet, though a certain person has been hassling them to do so!
For both the Z72 and the Plaza, just as Zig insisted on, leadpipes are carefully matched to the finished design at BAC, and the body of the horn is designed with next-gen modeling playing a role. Think of the Z72 as a second generation 1503 updated to today's tech (and with that @#*%%$^ BAC brace - nothing's perfect....) and the Plaza as an all-around "legit" horn.