Burntorange70, I just looked at this thread again. My opinion is that you are not overly rich with the plug you posted a picture of. Also, I would like to say mopar3762 is off base with his timing recommendations, he may have a fast car and the timing he is using may work for him but he didn't get there by a complete understanding of of internal combustion engine and how the cam and cylinder head design effect what the engine needs for timing to run most efficiently.
There are three pieces to the timing picture. Initial, mechanical (or centrifical) and vacuum advance. Initial + mechanical = what is referred to as total timing. From a performance standpoint the vacuum advance is not important since it does not work at WOT, under these conditions the manifold vacuum is close to zero much less than the 6-8 "Hg vacuum necessary to get the vacuum advance to start to move and add timing. Vacuum advance in the 60's and early 70's cars was there only to improve the part throttle light cruising efficiency (in the mid/late 70's the vacuum advance was used to advance or retard the timing for emissions purposes and usually had and electrical or temperature control in between it and the vacuum source).
In a stock mopar distributor if you peer below the point plate (or pickup plate) you will see a plate with slots in it the advance weights ride in. This is what controls the amount of mechanical advance in the distributor. If you look closely you should see a number stamped on it, double this number (remember distributor turns at 1/2 crank speed) to get the number of crank degrees built into the distributor. Also, stock distributors will have a light spring and a stiff spring that has a loop on one end that does not contact the advance weight. This allows the a two stage advance curve in some non performances engines all the timing may not be in to well past 4000 rpm. The vacuum advance will also have a number that when doubled will give you the advance built in the pot. The adjustment screw inside changes the preload on the spring that forces the arm back to the zero point. Adjusting this will impact the vacuum level at which the advance starts to move but and ultimately the amount of vacuum necessary to get to full stroke.
The MP performance vacuum advance distributor (they also sell a billet distributor with out a vacuum advance) outwardly looks like a stock distributor but for the last 5 years or so it has had a Mallory adjustable advance mechanism in side it. It is set up with 24 degrees of timing built in and the lightest pink springs which results in all the timing being in around 1800 rpm. The way it is set up is for it being installed in an otherwise stock engine where you will be running 10-12 degrees of initial timing. That gives you the 34-36 total that an open chamber sb head likes to see.
As you increase the duration of the cam beyond stock you need to add more initial timing to make up for the loss of efficiency due to the additional cam over lap. As the initial increases you need to reduce the mechanical in the distributor to maintain the 34-36 total. Setting the timing at rpm to 34-36 may work for a race engine but it leaves a lot of driveability on the table for a street car. The proper amount of initial gives much better throttle response and more power at the lower rpms. This is where the stall of the convertor has an impact. A high stall will allow the rpm to rev to the stall speed with little or no load, on a street car with a low stall speed the engine is loaded at a much lower rpm and if the timing is not correct it won't make as much power limiting perfromance.
The cylinder head has a direct baring on the total timing the engine wants. Open chamber heads that do not have a quench area do not mix the air/fuel as well and will require more timing to ensure that max cylinder pressure is obtained at 20 degrees after TDC, this is the point at which the most torque will be generated. Closed chamber heads like the magnum head can be set up easily with flat top pistons to have a very good quench and will require less total for max power.
Also, increasing compression generally requires less total timing than low compression engines.
If you get the timing all dialed in you will likely find it easier to fine tune the carb.
