Possible vapor lock or heat soak issue ?

My '74 dart sport just started producing issues that never have happened before. My dad drove it several weeks ago and after 10 minutes or so the car surges and sputters like it is out of gas. Started it up and drove it to the gas station around the corner and filled up with 11 gallons, so it had at least 5 in it when problem started. Attempted to drive it home and dies like it is out of fuel. He starts it and drives it a short distance until it dies and does this several times to limps the car back home to the driveway.

Today, i had the car idling in the driveway for about 10 minutes... No issues. Drive down the street... No issues. Then! When I decided it could possibly be fine I accelerate hard a couple of times and it started acting funny. I turned around immediately and it surges and dies I coast into someone's driveway. It cranks right up and drive about 100 feet and it dies... I did this several times until it just simply wouldn't start anymore.

We have driven this car several 100 miles after finally restoring it without much issue until now. I drove it for near an hour a couple of days before it started acting up when my dad drove it. We recently converted the ignition over to the GM hei kit supplied here
http://www.forabodiesonly.com/mopar/showthread.php?t=204177

Engine is a 360 with long tube headers, and radiator is a champion 3 core. Carb is a 750 Holley with mechanical fuel pump. Thank you for any help or suggestions!