Mbaird,
I can guarantee that your engine will idle better & have more vacuum with more timing with that cam & 360 cubes. My guess is 35-45* at idle will be optimum. You are going to this by electronic means? It needs to reduce timing as the engine comes under load or you could get detonation. That is why the simplicity of a vac adv unit is so good: it does this automatically.
I use vacuum advance hooked to manifold port. Actually my carb has no VA port . Why I don’t know since I told Patrick (Pro Systems ) this would be mainly a street car. So I plumbed one into the back of the plenum on the Victor .
The mechanical advance is digitally controlled.
The engine has 9” of vacuum at idle and I adjusted my VA to start at 10-11”s.