Fastest time with a 268dur cam?!

The reason so many people run a "268" is because its universal, as in it works over a wide variety of combos from low comp smog head, stock converter to 10-1 , good heads and 2400 converter...it just doesnt do any of it very well. You will be leaving horse power on the table if you use one.
If you call a good cam grinder with all your info, like Racer Brown, he can grind a cam for you that will out perform a "268" by a bunch, you will be happy you did and you will be faster than all the other "268" guys. Its a GM design from the 70's and you wouldnt listen to an 8 track instead of an MP3 would you? Do your engine a favor and get a custom cam ground to your exact combo.