Of course a MH will get you through flowering, but why would you waste all this time to produce a sub-par yield? If you want all the bud you can possibly get, grab an HPS bulb to swap out the MH.
I grew for years with a 1,000w MH, I still got huge buds and the frost was thicker on the buds. Anyway buy a fucking light bulb, buy 2. Dont ever get caught without a spare bulbs.