I am not an expert by any means, but it does appear there was more than one model in the 30's and possibly before. The part of the museum that you can go through they have roughly 165 bikes. In a storage area a couple of hundred feet from the museum they have 350 or maybe 450 more bikes, I can't remember the number. Those bikes are there so they can rotate bikes in and out of the museum so when you come back in a couple of years to visit again the exact same bikes will not be there, some will and some won't. I would encourage you to go to the museum if you are in the area it was worth the money. Looking at pictures is not like seeing them first hand. There is also a gift shop across the parking lot where you can stock up on souviners. And yes anything with the black and orange and Harley name is expensive.
The older ones were roped off I think, but no matter what you were not allowed real close any of them. There are some on the way out that you can sit on and have your picture taken. Even those I did not look at the odometer.