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???
Not to my knowledge, no. Since I have KNOWN of actual cases where people installed the wrong balancer on both 318s and 360s I am almost 100% certain that they will interchange physically. Now, what I AM unfamiliar with is the early setup to the late. The early setup used different timing covers and water pumps, so I am unsure about the balancer's physical interchangeability with the early stuff, but I think they will physically fit, too. Let me ask you this. Are you 100% SURE what you have is a 318 LA balancer?