Just completed a project on a 75 back in June. A week after I got it running I competed in a local twinshock event on it and had a lot of fun. I've got a modern montesa too. I'm surprised at how good a trials bike the little ty is, though I'm by no means an expert. tytrials in the uk has just about anything you might need and bjracing is also a good source. there are some others on this side of the pond too.
This is how it came to me.
It turned out really nice I think. It will never bring what I have in it, but it did win a local vintage show in the old dirt bike class. I had a great time doing it and riding it is a hoot too.