All sorts of things crop up in American collections. Look at Bruce Weiner's Microcar Museum in Madison, Georgia. The place is chockers with all these "little" cars, enough to make Ian Wilson jealous I'll bet.....and check this out, not one Dart, but a couple.
There are no Bolwells in America that I know of. There was one in California but that has returned to Australia (the wide bodied one) and that now resides in New South Wales. I have not heard of any JWFs over there either. However, Roo's Buchanan lives in Oregon and races in Historic events on the West Coast.