The connection requires that the stage actually travels through the core zone of the WHS
I have had a quick look at France's 49 WHS (other countries can be left until later?)
I think that 10 are "impossible" because of no road etc - Amiens Cathedral, Bourges Cathedral, Chartres Cathedral, Cordouan Lighthouse, Decorated cave of Pont d'Arc, French Austral Lands and Seas, Lagoons of New Caledonia, Pitons of Reunion, Saint-Savin sur Gartempe, Taputapuatea
I have 9 as "very unlikely" for the same reason ...but?? .....Belfries, Cistercian Abbey of Fontenay, Fortified City of Carcassonne, Prehistoric Pile Dwellings, Primeval Beech Forests, Pyrénées - Mont Perdu, The Architectural Work of Le Corbusier, Vézelay, Vézère Valley. Vezelay could just about be for a start, but I can find no record. Mont Perdu - there is a cycling web site which says the road has not been use. I am not sure it goes inside the core zone anyway.
I have 3 as "Probable" -Fontainebleau, Fortifications of Vauban, Versailles. All have roads which could be used which are inside the core zones
I have 22 as "almost certain" - but would need a lot of detailed work to establish Year and Stage etc ...which I don't wish to do!!
Canal du Midi (Over it?)
Causses and Cévennes
Chaîne des Puys
Great Spa Towns of Europe
Nord-Pas de Calais Mining Basin
Routes of Santiago de Compostela in France
And 4 which are definite as they came up during my quick Search
Gulf of Porto - 2013 Ajaccio to Calvi
Mont-Saint-Michel - 2016 Mont St Michel - Utah Beach
Paris, Banks of the Seine - last stage every year
Pont du Gard - Stage 17 2019 (Presumably went under it?)
Royal Saltworks of Arc-et-Senans - 2012 Stage 9 Time Trial Arc et Senans to Besancon
The last one shows a frequent problem for many of the "probables" - one needs a map of the "exact" route. Arc et Senans has roads inside the core zone which could easily have been used for the start of a TT...but were they? Similarly Fontainebleau has a road inside the core zone etc etc.
Does anyone have this book
and are its maps good enough??