I notice in computer controlled 258 (83 on) the the vacuum advance on the distributor distributor is connected to the manifold vacuum. Is this because the computer has some control over the advance? This would explain setting the timing at 1600 RPM with the 10" and 4" vacuum switch and vacuum hose disconnected.

So if you bypass the computer you should connect the vacuum advance up to a ported vacuum connection. Right?

IS there anything else special about the distributors used on the computerised 258 we should be aware of?