It won't cover, and it also probably won't focus to infinity, given the depth of the body of the 600SE.
I feel obligated to tell you that I think flat topping one of these cameras is not necessary, and IMHO, a waste of a good camera and good time. It doesn't give you any really helpful advantages, and it takes away quite a lot. It is also irreversible, as it is quite a hacking of the camera. All it gives you is a slightly lower profile and a little less weight. You still have a big and heavy camera in the grand scheme of things (it is 6x9 and made of metal, after all), and you still need to track down or fabricate a WA viewfinder, but now the camera can only be hyperfocal/scale focused (or on the Mamiya Press models, ground glass focused, if you have the ground glass back).
The coolest and most unique thing about the system is the coupled rangefinder focusing with several different lenses. Hack the RF, and you lose that, and might as well just have a 2x3 Graphic at that point. Smaller, lighter, more versatile, more common, and cheaper.
The way to reduce weight with this system, and still maintain its full function, is to get a Universal or a "plain" Press (as opposed to a Super 23). The Super 23 is the heaviest camera in the system (and also the coolest), due to the tilt/swing back. Additionally, you can shoot Polaroid (now Fujiroid only, of course) pack film with the Universal (and the 50mm will cover Polaroid and 4x5, which makes it even wider than it already is on 6x9).
Finally, the 600 SE is more rare and more valuable than any of the similar Mamiya Press cameras. I would never hack one unless it was thoroughly trashed to the point where it should just be thrown away.
IMHO, you are far better off with a 2x3 Crown/Speed/Century. They are cheap, and you will have very little problem getting them to focus at infinity with any lens. They are smaller than a flat-topped Press, and are much lighter, fold down, are more versatile, etc.