Here's a little reference you can check - hard to see in the pics, but the width of the balancer is slightly more than 1.50", plus the area around the hub (front face) projects another .250" to give it a total width of 1.750 from the back edge to the pulley mounting face. The inner hub should stop on the crank camshaft gear when fully seated - it's real tough to get it too deep, unless for some reason the crank gear is thinner than spec. If your current balancer measures up, you can eliminate that from the puzzle and start with the crank gear, and work out from there.
I have my original balancer hidden somewhere in the Black Hole of Calcutta (my garage), but I'm sure it is identical to the NOS House/Bedroom Closet Stock pictured here. If you need any additional measurements, let me know.