I always contact ATC with: "Cessna Businessliner N195**.." they think I am a 400 series twin...when I appear as a polished cantilever (strutless) monoplane with a radial engine it kinda surprises them...:o)
I love old aircraft, but when you're busy and you're trying to keep your pattern tight, an assumption on airspeed capabilities that later turns out wrong, can really get a lot of people in a jam.
Don't take it personal, but my faith in the FAA ain't what it should be.