Yes, I'd buy a threadless fork, Headset, stem etc. I know the races from the HS would fit the french bike, but would the 1" threadless steerer tube fit?

I don't know if its "disgusting" because its so non-vintage but my plan for this bike is the shameless and merciless combination of new technology with this old steel frame. best of both worlds, see? Like the Jay-Z/R.Kelley tour.