Stick with the stock plugs for the 216, and set the gap at .045". Set the initial timing to the BB just like the point-type distributor, disconnect the vacuum line, and rev the engine to about 2,000-2,500 RPM and use a delay-flash timing light to check for the maximum centrifugal advance. The combination of initial and centrifugal should top out at around 35-36 degrees. You might have to install a set of different springs in the centrifugal advance to allow the advance to max out at that speed, usually slightly weaker springs than standard. If the initial/centrifugal total advance is too low, adjust the distributor housing to get that number at cruise speed, and let the initial fall in there wherever it will. The total advance is more important than timing on the BB, as long as the engine doesn't kick back when starting. Connecting the vacuum should add about 8-10 degrees more advance at light-throttle cruise.
Jerry

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