I thought exactly the same thing and I came to the conclusion that currently there isn't a suitable taildragger for flight training.
120/140 are all pretty long in the tooth. There isn't a huge number of them around. Alot are on permit and those that are not the engines are out or high on time.
150/2 taildraggers again they aren't many around and of the ones that I am aware of are well and truly worn out.
I even emailed American Champion to see if they would be interested a putting a 80hp rotax in the champ but they never replied. Now that would be a good training aircraft.