We did a lot of yellow zinc on small electronics components that had tight hole tolerances and tiny threads. We would send a small sample lot with a few sizes and then measure when they got back to see how it went and determine our hole size from that.
The other option is very slightly oversize the hole and then ream after plating. Theoretically it should leave some plating there if the hole was big to begin with, but I never liked the practice myself. Not something I'd try on that big of a hole, that thick.
4140 will move around in heat treat so at less than one inch thick I would suggest getting your stock hardened and then cutting it in the hard state. 4140 still cuts great at 40-45HRc but start with decarb-free. I don't see a flatness or parallelism call on there so I assume you are just getting flame cut blanks and then punching the two holes and cutting the one end?