Hello,
I think the grips below on my Magnaport Custom 629 Classic PP are the same as the grips you refer to. They are very nice grips, as all Nill grips are. They are easily my favorite grips for revolvers. The quality is excellent and the fit is seamless where the halves fit together. I would recommend them HIGHLY, and i am not one of those guys who think's that whatever I use is wonderful, just because i purchased it.
I have medium hands but long fingers so these grips are not too large by any means. Grips are subjective, but I would classify the Nill grips that have the closed back as "large" generally, but not excessively so. Nill also has some models in an XL size and those are very large.
If you have a concern about the grips being too large, i would opt for one of the open back models, such as their open back replacement grip.
My hands down favorite Nill grip is on the lower PC 629 and is simply their smooth closed back replacement grip. That grip suits my hands just perfectly and it super sharp looking as well. The Hemphill model, upper gun pictured, is slightly smaller in that it has a more pronounced flare at the bottom and has a thinner center portion where your palms are.
If you wear a medium size glove, go for one of the open back models. I think those would be your most probable "perfect fit"
Coincidentally, I just recently ordered the SW038P competition grip for my inbound Performance Center 617 that will be arriving soon from Germany.
IC
i think the safer choice would be more like these (although the closed back Hemphill's may work for you):
http://us.nill-shop.com/Replacement-...oves-open-back