In CS’s build thread this gets discussed, his wife’s Gresch Honey Dipper has notches to receive the strings, my Dobro Hound Dog Deluxe has them also, I think mainly to maintain an even string spacing.
if you’ve a set of nut files it should be no probs, and as you are in Freo, I’m pretty sure Adam can sort you for those fairly quick.
https://www.pitbullguitars.com/shop/...-set-13-files/