Bob, I don't think anyone has a good estimate of how many were built, but I will take a guess.
I would bet less than 500. I base this on the fact that Simplex built so few bikes from 1959-1960. From some info I have, Simplex produced 820 bikes total for 1959-1960. At this time they were building footboard regular models, footboard Sportsman's, footage sportsman's, and scooters. Even if the "new" Sportsman was the most popular model at this time, they must have sold some of the original style and motor scooters.
Anyone else care to take a guess?
BTW Bob, did you happen to see my Sportsman at Portland?