It's not completely relevant, but I put the F&M on my O-300. The old kit instructions didn't give a torque value, and my mechanic says most people under torqued them and they leaked. The latest kit replaces one of the copper crush ring gaskets with a composite gasket, and also specifies a torque value of 65 ft. lbs. The few people I've talked to that complained about the F&M CO-300 adapter leaking said that they didn't torque it that figure.
The first problem was that the instructions said that if it was an old engine to run a tap into the hole where the screen came out before threading in the new adapter, otherwise the carbon in the threads would cause problems. We looked at each other, said "we got no tap", and scrubbed the threads in the hole with a little wire brush before threading in the adapter. It got about half way in, then seized up so tight we thought it would break trying to get it back out. Bought a tap (big bucks), threaded it in by hand, then threaded in the adapter with no problems whatsoever. If anyone wants to install the F&M CO-300 model, they're welcome to borrow my tap.
The next problem was trying to torque the adapter. It has a one inch square end on it, just like the plug that holds the screen. However, the torque wrench had a 1/2 in drive, and no sockets around that would fit the square adapter end. I ended up cutting a one inch square hole in a 3 inch circle of 1/4 inch plate steel, then welded that to an old bearing cup to make my own socket. I welded a 3/4 in. nut onto the back of the bearing cup, then put a 3/4 in. socket on the torque wrench, and that problem was solved. Socket is also available for borrowing.
It's been operating trouble free since that time.