Draco
I will do when I've removed it, the other half of the rocker is still held in place by the shaft.
It's the tips of the cams which should be shiny, the lobes, as that's where the metal to metal, cam to rocker pressure point is at it's highest, the second pic I posted is of the cam lobe of number 1 cylinder, the third is number 2
The rocker which broke is number 3, I don't want to turn the engine as the cars sat for 9 months with what appears to be no lubrication on the cam bearings and I don't want to cause any further damage,

I'd remove all the spark plugs, and turn the engine by the crank pulley or alternator to see how that feels. Just because it sat for nine months does not mean things are more seized than they otherwise were. You won't make things worse, and you will need to turn the crank to disassemble the top end if - as may well be needed - in order to check and fix things.

I don't suspect a complete blockage of oil to the cam, because if the cam bearings seized you'd have a whole lot more damage. But the blockage you have is bad enough.

Assuming it turns OK, do a leakdown on each cylinder and compare. You may well have a bit of a bend in that #3 exhaust, and if it leaks more than the others (especially the right side), you will need to pull the engine and at least remove that head to deal with the bent valve. If the comparative leakdowns are good, you have probably dodged the bullet, or at least part of it.

At a minimum you will want to pull all the rockers on the left bank to see how widespread the lack of oil was. How are the wear faces of the other rockers? The cam lobes? A blue cam lobe is not a good sign. The big worry here is whether this wore through the surface hardening enough to compromise the lobe. As noted, an unlubricated cam/rocker interface will penetrate the hardening, and when that happens the lobe will wear down very fast. I once saw a lobe which had fins on each side in the lobe's profile, but the center was worn down to the base circle.

Maybe only one of the oiling holes for the exhausts got plugged? But you have to ask, if that happened, where did the debris come from, and is there any more of it somewhere in the oil system waiting to cause mayhem elsewhere.

In any event, the break was most likely not caused by either an overrev/missed shift, or by a flaw in the rocker casting. If it had just snapped from one of those causes all that heat would not have been generated.