1995 GMC Jimmy Remove Carbon - Clean Engine

Dear RACEFAN966?,

My Jimmy has 221 K miles and presently is running pretty good. I am finding that the spark plugs are
accumulating much carbon build up, oil fouled, and bridged ash deposits. I have changed the spark plugs
3 times in the past 6 month's. Due to this accumulation. Presently, I am using the stock AC spark plug, prior I was using Bosch.
The Bosch did not seem to have as much of the previous mentioned deposits, but were reading as if they were the incorrect heat range - the reason I went to the stock spark plug. Would you suggest going back to Bosch? (Maybe I can be more critical in the heat range plug partnumber).
I performed a compression test and all cylinders read above average psi and all cylinders were very close in readings with each other ! Very Good for the age of the Engine.
Primarily, I would be looking to Clean and De- Carbon the Engine Components which I can get to with the Engine still in working order. Back to the topic of Valve Covers - since I have owned the vehicle since 2003 a valve cover has never been opened. I am not sure about previous owner, and possibly, the valve covers have never been opened.
I understand from readings that this Engine and All engines of this mileage will develop more Oil usage due to Piston Ring Wear and Valve Guide leakage - slop. Yes, I am using more Oil these days, not excessive, just more. Gas Mileage is close to the original stock specification. The Engine still has alot of power and I can cruise nicely on the Highway.
Can I open the valve covers and clean the upper parts of valve train and would this be a benefit?
Can I add a Engine Flush to the Engine while it is intact and let it sit in the Engine to soak a day or two
and then flush through similar to an oil change?
What are your suggestions of an engine with this mileage?
Thank You

Thanks for any suggestions.