The cam isn't directly under the bore, so it doesn't get any direct drain from the cylinder walls. It's shielded from splash a bit by the hanging cylinder wall.
The head drains into the pushrod compartment through the pushrod clearance holes, and this oil reaches the lobes through the annular tappet clearance. The amount of oil passing through here can be somewhat regulated by counter-sinking and enlarging the small drain holes located between the tappets, but I'm not sure this is helpful.
A pan scraper will block crank throw-off from reaching the cam from below.
