Dissapointing performance

There is a lot of gold in that statement!

If it has headers on it, remove the exhaust at the collector and see how it responds. The exhaust is KILLING the engine and NOTHING you do with the distributor will fix that. As long as you continue on the current path, accept the rotten performance you've observed.

That engine with a good tune, decent carb and exhaust will make 420hp EASY!!!

His headers are custom made 1 5/8" tube shorty's with 2" collectors. They would still kill the power output.
Out of the hole it's stall speed is so low it's not on the cam and when it gets on the cam it can't breathe worth a ****.

With a few changes to the driveline besides what you posted he can have a 420hp car that has traction issues. Then he'll have to tune the chassis to get it to hook so he can have a car that can haul ***.