I currently run M50s as mains with an M3 as center.

I normaly run the M3 vertical and inverted and it works great.

I sometimes(during the Hoildays)run the M3 on it's side and it does a good job in my assemetrically arayed listening room.

I just make sure to place the tweeter side toward the listeners off to the side.

The M3 is a lot smaller and elaborate than an M60 but the concept is still the same.

......hey, it's worth a shot, especially if your room is a little wierd!!