I read the description quickly and I didn't recall a wheel size specified. It is a nice frame. I looks like it had a Herse Bottom Bracket.
It looks like the owner, like most frame makers nowadays, didn't want hidden cables. That makes repairs on the road far easier. The owner also didn't specify remote control for the dynamo.
The only Herse specific detail not shown was whether or not the lighting wiring was internal. Maybe not. This bike appears to have lighting wiring routed through the fenders. I'm not sure if it has the steerer mounted eclariage san fil, an innovation I believe developed in a conference of the french constructeurs and the FFCT and effectively implemented by Herse and now Toei.
I'm surprised by the double water bottle mounts. That may be a modification. Through the 70's the ideas on hydration were primitive. One frame mounted bottle was often good enough, when considering the spacing of villages one was riding through in France.
The derailleur tab may be a modification. Not very many touring derailleurs had the tab in that location then. A first generation Huret Alvit would be period correct. Maybe it sported a rare Spirax! The right inside dropout is interesting. It looks like it it might be ready for a chain rest, but there is no chain rest. Herse sometime crafted front derailleur mounts to save a few grams on the clamp and maybe to lessen the stresses on the seat tube. I didn't see a front derailleur mount.
Herse seat stay brake bridge often had a bolt extending out. The fender was "nutted" to the frame. So this frame is a bit different than others I've seen. I don't think this detail calls into question the provenance.
It is a fine frame. If I didn't already have one, I might make an offer as it is within my size range. I'm happy to provide commentary and watch to see who will become the new proud owner. All it needs is paint, a bottom braket, cranks, maybe Herse brakes, a Herse Stem, and Herse crafted seat binder bolt.
I rode my '71 Herse over the weekend on a 200k brevet. It was a fine spring day and it was it's first long excursion on the bike for a while. It was pretty fast. Whether it was because the frame was Planing or whether the 28 mm Challenge Parigi Roubaix tires were providing such low resitance I don't know. It was an interesting to pedal up western Marin County hills then looking behind to see many on carbon bikes behind. They were probably just soaking in the scenery.
Todd Teachout
Hercules, CA