As the aim of timing is to get the best out of your engine, and because there are lots of variables which determine where the best timing exists - I always go and test it on the road. Find a long hill with more or less fixed gradient. Try running up the hill at a fixed and known throttle openning, do it again and agin with slightly diferent distributor locations you will fin dthe best position. I have a local hill which I use and using this method got speed from 40mph to just over 50mph by moving away by aparently 5degrees from the 'ideal'.
Your own rolling road!!!