Strange timing bracket. Application?

Just relocate the slot in the balancer..
Or if more convenient, relocate the TDC mark on the cover;piece of cake, and ZERO dollars. Unless you are looking to be year correct.
I myself have a 71 engine in a 68 chassis, with IIRC a 73 cover,a 70up Milodon waterpump, and unknown year Saginaw p/s pump.
I think the cast-in tabs began in 68, with the last year of the bolt-on tabs being 67. I think. But it really matters not. Listen; erip-erip-erip. That's the sound of the hacksaw;erip-erip-erip......lol