Hi Dave,
On my Gannet, the breather on the crankcase is fitted (from the factory) with a brass cap which has a pipe coming out at 90 degrees to the side of the engine. I simply fitted a piece of water cooling tube from this to the catch can.
With the extra balance weight, you have ended up with a pretty hefty boat, but it does look to be sailing well in the photos. The joy of the Gannet (and I suppose all "sparkies) is the number of variables that you can try to get the best performance. Change one and you have fun trying the rest of the settings to get the best out of it. Do give a bigger prop a try,as I think that you may be surprised how well the Gannet handles it. It also will keep the revs down a bit and preserve the life that the engine has on it.