[Steeveedee]

Check your rotor to see if it has a burn through. This is common with the HEI. If you have a badly worn plug or high resistance wire, the spark has to go somewhere. It can actually burn a hole through the rotor. Put a couple of drops of gas in the well below the center electrode and look for a wet spot, if the hole isn't obvious. The scorching of the plastic of the rotor can also make ready paths to other spark plug terminals in the distributor cap. It is possible that there is carbon tracking in the cap, from a worn button. You may not be able to see them with a black cap, but they would show up well on a red or brown cap. To be honest, the truck didn't sound that bad. One thing I did notice was a bog when you blipped the throttle. I see in this thread that there is provision from Holley for progressive linkage. I would use it, personally.

As for "weak" brakes, do you mean a hard pedal? If so, that's going to be a vacuum leak, I'll bet.