You're gonna have to unplug those wires. I have a 69, which is pretty much the same.
There is a clip that holds the main harness up against the back of the cluster; that is probably your main problem. I just snapped it off (it is plastic) and zip-tied the harness to the metal bracket just below the underside of the dash pad. This will allow the cluster to come forward a little more. There is a plug on the left side of the panel and one on the right; these can be removed with the cluster still in the dash if you have small enough hands to get in. You just have to wiggle them a little to get them off, but you have to be careful because the pins are fragile. The ammeter wires are the only other wires connected to the panel, but they come out of the main harness, so if you bust that clip you shouldn't have a problem with those.
One other thing is the wiper and headlight knobs: those might have to come off. I got my cluster out without removing them, but it would have been easier if I had, because the bottom of the panel was hanging up on them.
Hope this helps a little...
