hazetguy-
Like the seatpost fix, start with the simple and work up to the complex. Run a French threaded die over the fork threads to see if they can be re-profiled after first checking to see if someone has messed up the threads with an English or Italian force fit. If that fails, a framebuilder may be able to add braze to the threads and then re-profile them with a die. Last resort (you may be getting to know your local frame guy really well) the steerer tube can be shortened and a new, upper, threaded section Tigged into place. All in ascending order of complexity and cost. Tigging allows you to switch to English threads, as well. However,it all seems a bit of a pain when a new steerer and a coat of paint to the whole bike would save a lot of complexity. And the C 35 is definitely worth the effort. C 35 steerer replacement is discussed here:
https://bertinclassiccycles.wordpres...5-restoration/