pb84,
Some thoughts from my club's Chief Towpilot:
Boy it sure does sound like his oil ring is not doing the job based on his fouled lower plug and oil use.
The confusion is the hotter EGT on number 1 in flight. The EGT wouldn't be related the cylinder position but rather a leaner mixture on that cyl. There may be no relation with the two symptoms.
Question then. Why did they hone the cylinder in the first place? Did they hone all four and replace the rings on all four? So it was an top overhaul not a tear down inspection?
Are the cylinder serial numbers the same as they took off? Did #1 get a new different cylinder. May a cerminil or Chrome cylinder by mistake? If it was run in low, full throttle, and so forth then 25 hrs shd have the rings seated. I had a glazed cyl with the same symptoms but a good honing fixed it.
Sorry can't be of more help.