its not hard to do it yourself. i would start there. for a small block your want about 36° total timing in the plate. you need to weld up or braze the slots on the distributor closed a little until you get to the right setting. there is a number stamped into the plate. the number is the degrees advanced at the crank, so double that and you get your advance in the plate. measure the slot and then you do a little math... slot length*desired advance divided by plate number times 2. that will give you the new slot length. so a little brazing and some filing and you'll be good to go.