There are a couple distinctions that need to be made; First, between what is theoretically possible between a valve of a certain size, and an inlet opening of a certain size. Secondly, between what Mother Goose has built, and what is theoretically possible between the existing valve and existing inlet opening. On injected Guzzis, moving the port mouth is a huge undertaking, so we are realistically left modifying what's between the inlet and the valve. So no, there is no way to make a Guzzi (or 2-valve Ducati) flow as well a modern 2-valve automotive port, simply because the ports are not as straight. Laminar flow is a function of velocity and delta of direction; if the change of direction is too severe, flow separates and becomes turbulent. So because we can't move the ends of the port, we have very limited ability to reduce the severity of change of direction. I'll have to hunt in my data and see if I have a record of the stock cfm on my LeMans heads to compare with what's there now, and if somebody can come up with a stock V11 head data that would be interesting as well.
The thing about cams is that they're a lot of labor to change, relative to heads, they're not cheap, and ultimately still suffer the limitations of the stock heads.