Okay, I have a 406 sbc with 10.5:1 compression, MSD 6AL, Pro billet dist., Blaster 2 coil, 1 3/4 headers with 3 inch exhaust, Motown 220 iron heads, Super Victor intake. I will spin this motor approx. 6500 rpm. I will drive it primarally on the street with weekend track duty.                                                                                                     Now the question is what kind of heat range do I need to go with on my spark plugs. Any particular brand anyone prefer? What about gap?  

You want to get a heat range for iron heads. i'd say go with the spec plug for a '70 LT1.  

70 LT1 plug is a good place to start. From then on, all you can do is read the plugs and go up or down accordingly. As far as brand goes, your engine will tell you exactly what heat range it wants, but it has no clue what brand you put in, providing it's a quality product.  

PMJ76:
Okay, I have a 406 sbc with 10.5:1 compression, MSD 6AL, Pro billet dist., Blaster 2 coil, 1 3/4 headers with 3 inch exhaust, Motown 220 iron heads, Super Victor intake. I will spin this motor approx. 6500 rpm. I will drive it primarally on the street with weekend track duty.                                                                                                     Now the question is what kind of heat range do I need to go with on my spark plugs. Any particular brand anyone prefer? What about gap?

I think NGK will do bro.. But, why don't you try pulse plugs to.. I read that it emits 10 times the power of a traditional spark plug.. Try it out.. Maybe it can be of use to you.  

Pulstar plugs incorporate a mini capacitive discharge system into each plug. At about $50/set, narrowing down the correct heat range for your engine could get expensive (don't use an interchange chart from one brand to another, read the plugs). For the price of three sets of these you could buy a name brand CD system which will work with all spark plugs. CD simply produces a hotter spark, so beware of the exaggerated claims of increased mileage and power.  

Pulstar plugs incorporate a mini capacitive discharge system into each plug. At about $50/set, narrowing down the correct heat range for your engine could get expensive (don't use an interchange chart from one brand to another, read the plugs). For the price of three sets of these you could buy a name brand CD system which will work with all spark plugs. CD simply produces a hotter spark, so beware of the exaggerated claims of increased mileage and power.  

MSD 6AL is a CD (capacitive discharge) ignition system. Does anyone know where I can find some literature on how to read plugs? I know the basics such as you dont want sooty black or an ashy white color, but a nice tan color. But im just not sure about the the heat range. Are there any problems that could arise from an incorrect heat range? Thanx for everyones input.  

Go to www.dragstuff.com.  Search for the article "how to read plugs"