Kohler 3386-6 Rialto Skylight Round Front Toilet "drill bit sizes taps" Questions

...bit size so as not to crack porcelin. At Home Depot I bought a 1/4 x 20 x20mm "Insert Nut" and a good 2 part epoxy meant for metal and ceramic. Gently tap the Insert nut about 1/2 way into the hole ...