...there are some vintage types that can't be landed three point because the wings tip stall before the aircraft reaches the three point attitude...
What types are they?
I'm with you on this Chuck. A tailwheel conversion isn't complete unless you teach people both techniques, and most types on which people do tailwheel training are happy being wheeled, or three pointed, but we have to accept that there are some types that are not. In my view, you cannot complete the required training in those types, and you have to do the alternative landing technique in another type.
MJ