If you want to be 100% legal at all events run to Evo or Pre-82 rules, then you need to use the TLS brake from a Pre-1982 bike that came with no linkage, air cooling.
To the best of my knowledge, this means te angled lug brakes from any of the following:
1980 YZ465G;
1981 YZ250H;
1981 YZ465H.
The 1984 YZ125L also has an angled lug TLS front brake which is operationally identical, and would take an extremely well trained eye to pick from the earlier parts. I would argue that it is a legitimate carry-over part.
It appears that the National level of the sport, the current interpretation will allow other TLS front brakes l, including those fitted to 1982 and newer models.