For what it's worth, my opinion - and it is just that - would be it would not be sufficiently mounted.

4wd stat is a different shape to 2wd one, and it goes both left and right as opposed to just right as you look at it. In my mind, the hoses attached on both sides will put more pressure and vibrations on the stat than the single hose on 2wd. Therefore increasing the potential risk of leaks if not bolted on and sealed well enough.

And besides, if it didn't need the 3rd mounting point why would Ford/Cosworth change the design? Not worth the risk in my opinion.

Maybe the easiest way would be to have a thread drilled into the 2wd head? Not certain this is possible but would seem logical. Ask an engine builder for their advice as you may risk hitting a water jacket etc. And not worth ruining an engine over a stat housing.

cheeRS