Yes can just tap some 1/4" threads and plug those smog holes with some 1/4" allen screws.
Here are a set of the later 596 heads that I rebuilt myself, new valves and guide seals.
All the 360 head castings are all the same flow and port size, just different casting numbers.
View attachment 1715563747
The later 360 heads have the hardened seats so they don't sink the valves like your 915s did.
