The thermal vacuum advance switch (and similar devices) are part of the 70's era emissions systems. You can safely bypass or delete the switch unless you need it to pass visual inspections. For best efficiency and performance connect the distributor vacuum advance to the ported vacuum port on the carburetor. This will apply vaccum advance at idle and cruise, and almost no vaccum advance at full throttle.
Adjust your initial timing to obtain maximum manifold (unported) vacuum at ~1500-2000 rpm. Then road test. If it pings under load back the initial timing off bit by bit until the ping goes away.
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