The OEM spring now sits slightly compressed with the screw tip flush at the far end of the block:
That OEM screw head knurling leaves a bit to be desired, doesn’t it?
Actually boring the hole would be a remarkably tedious process for little gain. Instead, I lined up the block in the drill press using a ¼ inch drill (the OEM hole isn’t hard metric!) in the unthreaded section, enlarged it with progressively larger drills up to an O (0.316 inch = 8 mm), then finished with a P (0.323 in = 8.2 mm).
As it turned out, my guesstimated relaxed spring length was a bit off, so I turned a brass bushing to shorten the hole by 2 mm:
If I don’t mention it, nobody will ever know!
The original doodle, with close-enough sizes: