Your fuel pressure is too high, possibly blowing fuel past the needle and seat.
The Holley wants 6 psi at idle, with no less than 4 psi at top speed. At 10 psi, you'll want to install a pressure regulator.

 

I wanted to give everyone an update on the problem. I added a fuel pressure regulator to the system and replaced the fuel filter at the same time. I set the pressure to 5 PSI, but unfortunately it didn't make a difference. I had someone who knows about carburetors take a look at it. After messing with the timing and a few other tests, he said the carburetor was providing too much fuel. Instead of messing with rejetting the Holley, I decided to replace the carburetor with a remanned Edelbrock 600 CFM model and hooked it up over the weekend. That solved the majority of the problem and the car is running reasonably well now. It's still stuttering a little when I accelerate, but it sounds like a timing issue. I think a little tuning will get it where it needs to be. I do eventually want to step up to a multi-spark system to improve the system. I have a few new questions for the motor, but I'll start a new thread for that. Thanks to everyone who has posted on this topic. It's a great education for me to understand what to look for when troubleshooting.

 

im with craby on this one, sounds like timing chain to me.

 

Thanks. I do need to check the timing chain. I'm guessing it's still original and there is 115,000 miles on the car. I'm not sure if this is the original motor though as the VIN is not readable on the block and the engine has been painted yellow (poorly) at some time. I see there are options for swapping to timing belts or gears instead of chains. Anyone have experience with these? Maybe go a double chain instead?

I did a VERY simple timing adjustment last week and the car is accelerating much better than before. Still not 100% but much better. I need to do a little more research on how to do timing adjustment to know where it really needs to be for idle and total timing. Anyone know any good books or websites for this?