Land Rover Repair: 93 lwb, stepper motor, fresh oil

Question
Hi John. I have been slowly checking off the list of gremlins from my nice  no rust 93 lwb I shipped in from Texas. Love this thing.
The mysterious stepper motor code 48 comes and goes but seems to be dormant for now after repeated cleanings of the stepper motor (there was never any fluctuation in idle just check engine code). Adjusted base idle. Seems fine for now. fingers crossed it doesn't come back.
Here is the latest; we did a r 134 conversion which has been great. I had the a/c on high one day and low coolant light came on. I checked the level, and it was fine although when I opened the reservoir, what seemed like extra coolant came out. I drained a bit of that, cleaned the sensor, all was good. Then about a week later, with a/c on high, coolant light came on again. Then oil pressure light started flashing. I stopped the rover and coolant had come out from the top of the reservoir opening. A lot all over the street. But, no overheating. Mechanic said radiator is in good shape as is oil pump. Trying to figure what causes this. thanks for any advice.

Answer
You are describing the symptoms of mild overheating of a worn engine.  That's what it sounds like to me.  The first thing I would do is fit known fresh oil, and a mechanical gauge.  See what the idle pressure is when hot.  Check the temps with an IR thermometer.  You may be surprised by what you find