Erratic Timing

Yeah what he said, Check that by sawing the crank back and forth, engine off of course, against the valve springs. Try not to move the cam. Any play at all is not good. But if you rotate the engine to get the balancer lined up with the index, you will be able to read the cam chain stretch in degrees. Two degrees is kindof normal . By 4 or 5 it's getting to be risky business with factory 318LA chain. Risky in that when it jumps it sometimes spells the end of the engine with at least 8 bent valves.
As to the D if the flyweight are not sticking,then she is fine.... except your thinking is correct; 30* in the D is correct for an Idle timing of 5*.
The engine depending on what it is, you didn't say, will be much happier with double to triple that 5*. But then you have to shorten the slots to take out the equivalent amount of timing for to set the power-timing, which,generally, must not exceed 36 degrees.
That one long loop spring is a tricky bugger. It is usually worth about 4* but may not give it all until 4000 rpm or higher. Because only one spring is now handling everything else, it is sometimes too fast after the initial-reset, to keep your engine out of detonation. So you gotta be careful in how much you can do on a stock engine.
Oh wait, you did say; I see it's a 318; which is what I assumed,lol.
As to the worn pins, I have brazed some hard brass on there which lasts I guess forever cuz no one has ever come back yet,lol.