They do fit (sort of) and work as desired.
The original, pre-magwell, factory rubber grips are narrower (side-to-side, across the face) about 1/16 at the top right (left side grip) and about 1/8 at the lower left (front-facing tail), so not a factory-designed match.
They extend forward at the front/bottom, towards the muzzle (left side grip), parallel to the frame line at the top w/ 1/8 margin to the edge, and no gap at the bottom/ tail, coming right up to the edge of the frame. The rear edge nicely follows parallel to the frame edge with the same, consistent margin as the original.
And, same palm swells but no recess for the mag release. But I have a extended release.
Overall, not huge issues since I was looking for, and found, the rubber-grip feel I wanted.
All that said, as I look at the result, my OSD may kick in and I grab my X-Acto knife and VERY carefully cut them to fit... Feeling more like that ever minute I think about it. At least if that doesn't work, I can always buy another set of the originals and try again...and again...