Hey Marc, IYWMO
Save your frig'n money man, a 27gl doesn't need anymore
Instead, save the cash and use it on your next setup, as your 75gl will cost you even more $$$. Also some may say you could use the new 150MH's on your 75, I think you would need at least 2x250 instead-so keep the 27 for the sump or you use it as a species tank or the mixed reef that you have right now!