As long as you have the hole to fill anyway I don't see a reason not to use the distributor for a cam signal. If you didn't want to for some reason I'm sure you could mount a cam signal in the timing cover and put a tab on the cam gear to get a signal. I want to say my 318 magnum had a boss and a filled hole cast into it for a sensor, but I could be remembering something else.
I though I saw you mounting LS2 coils, so I was through off by the distributor cap. Either way, looking good.
-Jon