318 head porting for the average joe

There's a thread where I flowed the 302 head. It wasn't decent till the valve got passed the chamber side of the head, .500 or so.

The cam could be marginalized by the shrouding. Take it to a shop and have them drop maybe a 2" stone intake and a 1 5/8-1 7/8 exhaust to unshroud them 1st, at least.
Otherwise you're wasting the effort.
Have them do a valve job like in my avatar... That's a 302 head just that valve job and unshroud, does like 190cfm. They can all do that.