The “problem” with your current set up is, someone used a spring pocket cutter with a non-standard ID(.597).

The two std sizes are .630 and .570.
Easiest solution is to just use a spring pocket cutter with an ID of .570 and trim your guide bosses down to that size, then you’ll have all kind of options for spring cups or seats.

Unless you’re running longer than stock valves, you’re likely going to find it a challenge to achieve 2.00” installed height with the typical beehive type retainer.
If you were planning on using a shorter installed height anyway, you might be fine.

While the .630 hole around the .597 boss isn’t ideal, it’s not the end of the world either.
I’ve seen numerous aftermarket import heads come with .630 ID locators sitting on .570 guides.

Many aftermarket single springs installed on oe heads often swim around that much.