The Cleveland crankshaft snout is "slightly" larger in OD than the Windsor crankshaft snout, so the balancers are not interchangeable, although you can slip the Cleveland balancer onto a Windsor crank. Don't hold me to these numbers but from memory I believe the Windsor crankshaft snout is 1.3775" OD, the Cleveland crankshaft snout is 1.3805" OD (0.003" difference).
John, you can have your balancer rebuilt by Damper Dudes for about $150 (I think), or for $300 pick up a premium balancer from Romac or ATI.
Operating your Pantera with a 30 year old balancer is not a good idea, and the ring may have slipped. Of course, you can always set your initial timing the way I have mentioned in the past and you don't need to observe the marks on the balancer anyway.
George