What kind of frame do you have? You won't be able to use a 1 1/8" fork with a frame that is designed for 1". You CAN use a 1" fork with a 1 1/8" frame, but it'll require extra parts, and the thin fork may look awkward paired up with the frame's burlier tubing. It's better to just use a fork with the appropriate steertube size.

Anyways, there are many more threadless stem options in 1 1/8", so it'll probably be easier to find one you like in that size. Just use it with a shim to run it with a 1" fork, if that's what your bike allows. Not uncommon.

I think the 3T mutant looks kind of quill-ish.