If anything, I believe Kimber would be the ones to use an odd radius. They're the ones who think they're oh so special, I could see that happening. And I'm not trying to knock them, I just think they're overpriced for what you get: a 1911 that's really no more special than any other, but they refuse to even talk to some people about warranty work until you've fired 500+ rounds to break it in (I'm a firm believer that all guns should run 100% straight from the box), and you better not even change the grips if you wanna hang onto that piddlin' little one year warranty (I'm also a firm believer
that a high end product should be warrantied for life, buck does it with their knives, why won't Kimber do it with $1000+ guns? A large majority of gun makers have a lifetime warranty).
But, the old GI style grip safety uses a different radius than beaver tail safeties, and I think almost all makers use "one or the other", and I don't THINK it's springfield that would use some strange proprietary radius.
(edit to add: I'll be changing mine up soon, so I guess I'll find out...I have a springer)
If he's putting a springfield beaver tail on a Kimber that currently has the old GI grip safety, he would need fitting regardless of the makers. Do they even make one that doesn't come with a beaver tail?