if the slots are being welded up a person needs to keep in mind that .0154" is one distributor degree. the pin on the centrifugal weight is real close to .25". so, if you want 9 distributor degrees for example all you need is a 9/64" drill bit to fit between the open section of the slot and the centrifugal weight pin. very simple, no special timing lights or anything needed. it's always best to set total timing in a performance application but by simply doing the math initial timing settings will get you pretty close to the desired total. I've been doing this for decades on mopar distributors; it's not rocket science.