The stock Vortec exhaust port isn't so bad. It's on the small side.
On most any small block Chevy exhaust port, the floor area is a low flow area. If you create a velocity probe and run some air through the port, you will see what I mean. The roof area is the busiest part of the port, so that's where you need to work.
Anytime airflow has to negotiate a turn, it almost always helps to widen the port area where the turn is negotiated, thus widening the port in the bend or radius area helps.
Chevy exhaust ports are easy to improve, and are easily accessible. I can do a full race port job on 8 exhaust portsin 3 hours. The intakes are tougher IMOP.