! Found the Real Problem ! - Timing

[PHOENIX]

This is a continuation of my timing problems I have been having.
Even with the new #1TDC mark I still have rough idle and valve clacking and pinging at low rpms (3000rpm+).
Driving me nucking futs.
Well I decide to pull all the plugs again and check them because the #4 cylinder before had the damaged and fouled plug. Well I pull all the plugs and #4 is starting to have the same problem again, all others look fine. I have less then 10 miles on these new plugs. See the picture below.
Old (Bad) = The plug from cylinder #4 that I had in for awhile and pulled out when finding the #1TDC
New (Bad) = The plug that's currently in cylinder #4 that has only been in for less then 10 miles and is already showing oil fouling).
New (Good) = The plug that's currently in cylinder #3 that is in good shape. All the old plugs except that in cylinder #4 looked good like this "new (good)" one.

So here is my questions.
(1) Do I have a worn piston ring, bad valves, or bad valve seals?
My guess is bad valve seals or valves.
The truck has been run low on oil (1 to 1-1/2 qrts) a few times in the last few months due to me being a slacker. Ill check it every other weekend or so and its anywhere from 1/2 qrt to 1-1/2 qrts low. To make a long story short my old valve covers had a baffle that restricted oil input, so adding oil was a b*tch and I slacked on change the covers (because the baffler and possibly bent covers).

(2) Where do I go from here and how can I figure out which (rings or valves) it is?
I'm guessing its time to pull the heads and take them to a machine shop?
Please help me out.
Thanks, Eddie

[Bowed]

Take a compression test .How many miles on the engine ? .

[PHOENIX]

I should be able to borrow a tester and check the compression.

Miles is actually unknown. When I removed the 305 and installed the 350 we wrote down the miles. The when I replaced the original gauges with the Autometers I wrote down the miles. I cant find either paper where we wrote down the miles. So I am guessing 60,000 to 80,000 miles on the engine.

What sounds like its most likely causing my problems?

[MylilBowTie]

possibley an intake gasket?

Leak down tester would be better to find out if its the valves or rings.

[PHOENIX]

After reading some stuff online I agree that a leak down test seems like the better test for this situation. I have compiled the instructions below from what I have found online, tell me if I have anything wrong.
Never done a leak down test myself so does this all sound right?

CYLINDER LEAK DOWN TESTING

Getting Ready for Testing and Testing:
Remove all spark plugs.
With all spark plugs removed you can turn the engine by hand at the crank bolt with a large ratchet and socket.
Cylinder being tested must be on the compression stroke (intake and exhaust valves closed).
Install leak down tester in spark plug hole of cylinder to be tested - always follow instructions with tester.
Re-test with piston located at different heights in the cylinder (for cylinder wall damage), but make sure you are still on the compression stroke.

Acceptable Amounts of Leakage:
All cylinders leak a little. Large ones leak more, smaller ones leak less.
Racing cylinders lose only 1 to 2%.
Production multi-cylinder engines in good condition will leak 5% and less.
More than 10% leak down means there's something wrong.

Understanding Leakage Indications:
Hissing (air leak) in the carburetor indicate burnt, tight, or carbon build up on intake valves.
Hissing (air leak) in the exhaust indicates exhaust valves.
Hissing (air leak) coming out of the dipstick hole or valve covers indicates worn or heat-softened rings.
Hissing (air leak) escaping from an adjacent spark plug hole indicates a blown head gasket.

thanks!!!