Better get some lightning protection in place, your masts are now the high point of that building unless there is an elevator room or cooling tower out of view. My recommendation would be to bolt a 10' copper-plated ground rod upside-down on the middle of the opposite side of that ventilator box and connected via copper strap to building steel if you can get to it at the base of the ventilator. A couple Polyphaser RGT's bolted to the masts to couple your antenna pig-tails to your down lead might be a good idea, too. Other than that it should be a pretty banging site... assuming it doesn't get "banged".