Schematic etc contact set supplier.As regards cooling tower its ok to locate it on top.Now a days most of the utilities are located in Terrace which is otherwise wasted .

Go to the website of Cummins, Caterpillar and MTU Detroit Diesel. Go to Generator sets. Look up "Literature" and other technical publications. The cooling system mounted several floors above the engine will cause excessive static head on the water pump seal. The manufacturer will have recommendations for cooling on a roof, and engine below, a common setup. Any supplier will be happy to come visit you and make recommendations face to face.