Playing with Distributors isn't really necessary or worthwhile except for a couple of reasons:

You have Vac. Retard and it bothers you
You motor delivers advance where you don't really need it.

For instance, an A cam in a B18
A dizzy with advance that ends before say 1500 rpms isn't going to make a lot of difference if the cam is meant for low-end torque. 003 or something which delivers total advance after 3k rpms might be more sensible.

A D or K cam, the engine seems to benefit from advance before 1700rpm. Surprise! that's what they came with.

C I guess could go either way, largely depends on other aspects of the drivetrain.

this is all very subjective. if you time the engine at approx 3k rpms, most if not all the advance is over with, and it's the dynamic timing which is the benchmark for what to expect of the motor. They'll run with any Dizzy that spins the right way, you might not get the whole benefit static timing, but it will work.

Personally I prefer the mechanical advance units, with low-end curves, because I swap components relentlessly, and my cars are all pretty much city drivers. My HS6 and DCOE carbs have no provisions for vac. Modular, mechanical things are big pluses for me.

But, now I'm putting in a B20F w/ a D cam in the '66, and my B18 003 will be set aside for a 078 vac retard, because the 078 curve is shorter. And my 003 is frankensteined parts.

The best dizzy is the one you have that isn't broken!
-Sean
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1966 122s, 1970 142s, 1974 142e... Blue is Beautiful