Engine/Prop: IO-375 with RV200

Another lazy Sunday thinking about engines and props....

I was looking at the IO-375. I'm building with a showplanes cowl so the RV200 prop looks attractive because I think it can incorporate the needed 2" length without adding a spacer. I like the 375 as a beefed up 360.

But the Whirlwind site says the RV200 isn't compatible with the IO-375. Anybody know why?

edited: found this https://vansairforce.net/community/showthread.php?t=179921
I guess I have to see about counterweights or not

Yup, the counterweights are the key. IIRC when I was talking with Titan about my -370 the high-compression option is counterweighted, but the lower one isn't. I was already planning on high compression so it worked out for me to go with the WW prop. (though I got a 300-72)