There is other reason too what can cause black plugs, look and read link about spark plug basics what I posted before. It it written by NGK and there is good info even if you think you know everything already.
I know from fuel mileage and exhaust gas smell (yes Im that hard core tuner) that its not pig rich. I have also setted fuel screws to optimal settings. Carb is almost new and has worked before so I dont think It can be pig rich.
And if you know how engine works with big camshaft youd know that there is always exhaust reversion in low rpm/idle. Always.
Iv been bussy at work I dont have compression test done yet. The shorty headers suck for performance I know. You dont need to tell it to me after I show the pics to you. They are like normal headers but short primaries maybe 10" and collector is 2.5" and it tapers fast to 2"
