Even people who are pretty good at this stuff are iffy about messing with emulsion.
That said, what they generally say is leave it like the original Holley setup.
It should be pretty easy in your case.
Leave the highest hole as is and plug the second from the top.
Then leave one of the two lower...
I was just going to ask that!
They are odd blocks.
So what you have is three emulsion holes vs the two that I talked about.
They're kind of semi-adjustable, meaning the holes are fixed, but you can install a set screw that has a smaller hole.
Is the highest of the four holes about the level...
Cruise with a cam like that will probably be happier a few hundred RPM higher.
Have you thought about swapping on the 650 on to see how it runs?
It that a vacuum secondary?