Well that’s the best I can do on this set of heads.

Idk, but hear you don't want to go bigger than 52.5 percent, but you talking stock valve guide location?
Is that 52-1/2% of the bore size? That would be a 2.14 intake, which I guarantee would take “A LOT” of finagling to get to fit the chambers. I’ve been told 2.08 will usually clear without doing anything drastic with guide location in most heads.