If you want to use the holes around the rim of the standard Lycoming flywheel, you want a box of various lengths of AN4 bolts - the minimum length will be -7 because of the thickness of the flywheel. You can go up in length from there, but only a couple of dash numbers or you can start interfering with the cowl. Then get some different styles of AN4 all-metal lock nuts, so that you have different weights available, as well as a handful of washers - standard, thin, and larger fender washers, all AN4. That’s basically what I have in my balancing box.
I also have some drilled out AN4-7A bolts for if I need to go just a touch lighter - you can see a Kneeboard Note I wrote last week on the Kitplanes website for more details. (BTW - someone took me to task for reducing the strength of the bolts by drilling the shanks, so I did some twist-off testing, and I stripped the threads off the bolt and out of the nuts before I broke the bolt.....)
Paul