The OH is is what will kill your engine.
.......

 

So now that we have the obvious out of the way, when I can hook up a propper scanner to monitor the engine, what else should I be looking for that's going to help me get to the bottom of this?

 

I believe you issues are unrelated.
Replace the plug of the cylinder with misfire and go from there. If it get you by for days then its the plug. If not replace coils, wires and plugs all same time. That is a bad misfire.
As you mentioned you checked the cylinder and no signs of coolant, it also depends where the piston is located upon inspection after the engine cooled down. I just hope its not early stages of cracked block.
Or, I think you have another bad thermostat like mentioned above. Its more likely to have misfires when thermostat is broken and open all the time since the engine wont warm up completely. Cooling system is still a complete mystery to me. Tow of my discos have water fall sound each time you hit the gas but it never overheat. Other have tiny hole on top of the radiator and never overheat and the last have a tiny hole on top of the reservoir and still never overheat. But, when they have bad stuck thermostat, they will definitely overheat.

 

I did try swapping the plug, so I can rule that out. I'm going to swap the wire over to the other side to see if the misfire moves with it. I hate just throwing parts at stuff to see if it fixes things.

Flushed the cooling system as well, and compared my new 180 tstat with the old one and when I run boiling water through them the new one is definitely outperforming the old. Hopefully that cures the over heat. I'll also have a propper scanner here tomorrow so I can monitor what's happening better.

 

Anything in particular I should monitor now that I have the ability to pull live data?

 

I had the exact same problem with mine. It was the head gasket.

They leaked so slowly that the steaming effect was minimal, really unnoticiable without the heads off to see all of them at once.

302, 304, and 303 and 305 all are close to the water jacket, it seeps in.

The Rover coolant level holds up well, but every few days it would burn off enough to cause a temp issue.

Top off and it is fine but repeats. Once I opened her up, they gasket was obvious.

One thing of note, my Rover was a beast. I did my hg at 200k, they were original gaskets. Feedback on the leak and causes were easy to spot with them.

A few misleading things happened in between my discovery of this. Intake heater and hoses failed, threw me off, a hose was old and busted, also threw me off, and my heater core failed, also threw me off.