HELP!! need experts advice on 440 trouble.

My best guess is there is something between the intake or exhaust valve and seat on #4 cylinder causing it to not be closing properly.
This could be why the plug is cleaner than most and why the compression is slightly lower on this one cylinder only.
Doing a leakdown test will tell you for sure.
If you don't have a leakdown tester, you can always us an old spark plug, break out the porceline and weld an air fitting to it, put the engine at TDC and pump compressed air into it. If you hear air leaking out the exhaust, the valve is faulty or hung up, air leaking through the intake/carb, intake valve faulty or hung up, air through the oil filler cap, it's the rings or piston.
I've seen bits of gasket material etc. caught in the valves do this before. It doesn't take much.
Hope this helps,
Let us know how it turns out.
Tom.