Is the throttle supposed to be this sensitive?

My son's slant six-powered Dart Sport has the Super Six with Carter BBD. As he backed it out of the shop and pulled it around behind the trailer to load up for a trip to the paint shop, it kept spinning out in the gravel and dirt. I got in to drive it up onto the trailer, and as he said, just the slightest tap on the throttle made it spin the tires and lurch forward. It was very twitchy getting it up on the trailer.

In addition to the Super Six, we put in a new Comp Cams 264S-10, and had the cylinders bored 0.030" over and had the A-904 freshened up. We never drove the car before all this work began, so I don't have a point of reference. Is this throttle sensitivity normal, or is there something that needs adjusting?

Jerry