Cam timing
Typically speaking on a modern single cam engine putting the cam in 180 degrees off won't effect it as long as it is EXACTLY 180 deg off. TDC on any current design is when the piston is up at the very top of the cylinder, doesn't matter if it's when the points fire anymore. Timing the camshaft means putting the cam in so the lobes are either faced toward the piston or or away from the piston, just so that the timing marks on the sprocket lines up correctly. Putting lobes down so they are away from the rocker arms is the best way, then you're not fighting the valve spring's pressures. Unless it's a Honda under head cam, then you have only one way to put the cam in, with a BFH!!!!!
That help?
Tony