My opinion - but it will leave the ends of the tank fairly dim compared to the middle w/ just 1.
I'd pay a lot of attention to the reflector if going with just 1 bulb - as getting a wide, and even, spread would be important visually and to maximize the space you could grow light-demanding corals.
For example - this isn't even the `best' reflector out there IMO - but for this size tank [and 2 MH on it] with supplimentals it was what was available at the time.
--- 2 year old pic, when I ran 175's ... ----
Here's a pic with 1 MH on a white, plain reflector vs. same light + tank with a better reflector. The amount of light in the tank's corners is significantly changed - plus much less a `hot spot' directly below the lamp.
As said before, pay attention to the reflector, IMO.
Only change is the reflector ...
FWIW, here's a pic with 2 MH's + VHO actinic [vs 1 MH + PC actinic as above]: