My suggestion.
That cam is only ~220 at .050 so it's relatively small on duration/overlap.
Get an A/F meter and see what the cruise ratio is running. I bet it's really rich on cruise and needs some dialing in. If it's running in the 12's and you get it into the low-mid 14's it will help the mileage.
Tune up has a huge effect on mileage. Unfortunately, people that think they are positively spot on for a tune up are not close. Cars will run with all sorts of off base tune up.