Don’t do it.
Trust me. The belt will wear into the shape and once it wear in, shit gets weird.
1st off, steep cheeks aren’t a great way to variate. But it’s required with frenchies cuz it’s the only way to get big variation (cheeks coming together as much as possible)
The problem with matching to a steep cheek is this. Mismatched belt to cheek is fine, shifts great. If you match steep cheek angle to belt angle, the belt will not shift well. It resists shift as it does not want to move up the cheek. I have done extensive testing with this. One can use mismatched cheeks like a steepy on one side then a less steep 15deg on the other. The 15 standard side will allow the belt to climb easily and shift well, with the steep side pushing the belt up that stock angle side. Now if both are steep, and the belt is steep too, the belt just gets pinched and can’t move easily. Belts don’t like to climb vertical walls. It’s simple physics.
However, the limitations with the archaic French shift design demands these accommodations if you want the large variation so you can run very short gearing but variate very far. Even 2mm difference in belt height at top variation means many more mph.
This knowledge sounds obvious in hindsight, but I tested multiple cheek angles over the course of a few years from 7.5deg-16 deg. And then tested belts matching those angles and unmatched. It taught me a lot about variation.
Another interesting note to this:
A clutch pulley works great for French bikes because that thin belt grip area wont be abused and slip at the vari boss, the large pulley with its exceptional grip is the main grip point, the fixed non clutch er3 or other vari just spins the pulley up and the pulley is where the clutch engagement happens with little chance of slip