318 balancer on a 360 crank advice needed

Please pay no attention to the balance issues that are inherent here. I am trying to mock up some pulleys and spacers to solve a custom accessory issue on a car that is 3000 miles away that has a 318, so I was going to use an engine that a friend has on a stand. The engine is a externally balanced 360 and all the stuff I was using for the mock up is from an internally balanced 318. When I put the 318 balancer on the 360 and tightened it up it doesn't seem to want to get as close to the timing cover as needed. It seems about a quarter inch off and that won't work because then the crank pulley would not be in the proper location. Is the 'snout' of the crank on a 360 longer or somehow different than on a 318 crank???