With valves this large, the shrouding occurs against the wall of the cylinder. There you can't do much about it. The only thing you can do is notch the block.
The same thing happens to the 427 Fords and the 427 Chevys for basically the same reason. Big 2.19" intake valves with too small of a bore.
Some intakes are run up to 2.30" diameters.
The Cleveland is a little worse since it really for all intents and purposes has 7 liter intake valves. 4.000" bore vs. 4.23" bore in the BB.
You, we, all of us, are "trying to get a silk purse out of a sows ear". You just can't get perfection. There is always a compromise.
If you really want to carry this to extremes, I've seen the valves and seats with 5 angle cuts on them.
When you need to reseat the valves you need to bring them to the "head guy" because he has to reblend the bottom cuts into the ports without modifying the flow.
It becomes alchemy. Trying to get gold out of lead.
Incidentally, the EPN valves only come with one cut on them. They need at least two more, one top, one bottom. You have to hold the seat width and the "margin" on the top edge.
This is all stuff that was done on the old "Trans-Am" cars back in the day. Labor was $7/hour.
Don't ask me to do them. I just sold a $5,000 machine for $250 because no body does this stuff anymore. Not even me.
The iron Cleveland 4v head DOES show improvement with a nice 3 angle seat and will flow something like 298-300 cfm @ .600" intake.
You don't need more. That's just an academic exercise?
Oh...I would also "petition the court" that the bronze guide in picture #1 has been cut back too much. You NEED to maintain a .100" margin there on the wall thickness of the guide otherwise you will wind up with the same type of guide failure that started this entire "mess".
I can testify that removing the ring will give you better results, or stated differently, the results you would expect from giving the heads this much attention.
The ring essentially reduces the size of the 2.19 intake valve probably down to between 2.02 and 1.94, the size of the big Windsor valves.
There IS one portion of the Cleveland RPM range where they will just pull away from seemingly anything not supercharged.
That's where the ports and the big valves are working. It's kind of unique to a 5.7 Cleveland, what Ford conceived of and what they really are all about.