Personally if I was firing up with a new cam, I would leave the timing to your existing setup intitially.. as Fitech recommends, then once the fuel system is working to your liking, you switch over to let it control timing as well.
Already broke in the cam with the previous crappy TBI. Installed a new distributor and got rid of the HEI GM stuff as well after the cam was broken in.
I have an MSD adjustable rotor on the way so I should be able to fiddle with it and get things squared away.