As a former "parts counterman" (some 15 years at two stores) just use the age old "They're all the same"
I got into one HELL of a mess with a drunk *** over a 350 vs 400 Chev, whatever he wanted it made a difference. "How do you tell?" I said look at the VIN you can not tell by just looking at the engine. "Bullshit there's no way you could get a 400 out of that little engine"
Yeh, well OK fine