Vacuum Advance / Boost Retard unit

I have read that you can use the vacuum advance pot but under boost conditions you need to have a check valve installed between the source and the dizzy. If you are boosted its is best to use a mechanical dizzy and something like a MSD BTM to retard per # of boost that way you won't risk detonation! I can't seem to find anyone that times the curves on dizzies anymore. I guess everyone junked their Sun machines???

There are some threads on TTF about this exact issue.