Actually, more USRA loco were built after the first allocations, as "copies" and later "based ons". This varied with type, but the USRA Light Pacific was a widespread basis. Also, the USRA-ness of a loco was not so much the surface appearance as it was the specs and dimensions
The beautiful USRA 2-6-6-2, popular with us modelers, was never copied, and only 30 were ever built.
Unfortunately, MTH in particular insists on calling its USRA 4-6-2 a "USRA Heavy Pacific", but it is actually more the Light Pacific above than the Heavy.
The old Samhongsa Williams brass USRA Pacific was pretty much a Heavy. Bigger boiler, different, lower domes. A huskier look.