It is possible to use a vertical vanguard and flip it on its side, you need the pick up tube and oil pump from a horizontal engine and carb, spacer and bolts from horizontal. Also you will have to fabricate an oil dip stick and plug off the old hole. As mentioned it would be easier and cheaper to find a horizontal engine, the crankshafts are lighter because they are over an inch shorter and they have bearings on the pto side as well.