Master Airscrew 7X4 -3series, OS A-3 plug, Sig 15% Champion fuel. Cold , Wet , Rainy day. 15,000

That's a good rpm number. I haven't used the GF3 on mine, only the older wider MAS props and had lower revs than that from what I can remember.

What's it going into?

The GF3 drags the engine down a little more than the older series. They may be a little stiffer.
I would love to be able to use this little engine in a Herr Pitts from Sig.

Yes, that sounds like a good match. I have one of those kits too, just have to finish a few other projects first...

Ihave a lot of other projects and training in front of that one.