The eccentric shim Daniel recommended should work nicely. It’s the Jtek Eccentric Front Mech Shim if you need to source it outside of the us.
Another option could be to use the Salsa Custom FD Mount they made for the cutthroat. Could be cool to see that piece on a metal frame! Since it’s made for a carbon frame, it’s entirely possible it won’t work with a round tube but it’s cheap enough to purchase and try out for fun.
If you’re looking for good crank and bb options, there has been discussion about this topic on the 29-er Gravel Bike with Boost Spacing - What Drivetrain?! thread.
