I don't believe the Ruger GP100 in .327 mag will shoot .32ACP. May only shoot .327 mag, .32 H&R, .32 S&W, and .32 S&W Long. Better check further on that.
But I'm pretty sure shooting a .32 S&W in a GP100 will be about as low recoil as you can get.
Edit: Changing my opinion. It should shoot the 32ACP as it is semi-rimless but you may have extraction issues.