It is a fact that the steering gear valve (or the control valve on C2/C3 Corvettes) is the primary component that affects steering effort and feel. However, the amount of flow from the power steering pump can also have some affect as well.
Cutting back the flow from the power steering pump by changing to a production type discharge fitting from one of the above suppliers is a good idea. Most Camaro systems were probably in the 2.5 gallon per minute range. This would be a discharge fitting with a throat diameter of around 0.130 inch. Too much flow can make your steering feel light and twitchy as you drive down the road.
The only time that you would want to increase the pressure relief of a pump (i.e. remove shims from the back of the flow control valve) would be if you did not have power assist as you turned your steering wheel to near full lock with the car stopped (held in place with your brakes) and the engine running. If you have full assist with this type of maneuver, you have sufficient, or possibly even too much assist from your pump.
When you are driving down the road and making steering motions, you probably aren't requiring more that a couple hundred psi of pump boost. You will not even be close to pump pressure relief. So pressure relief has nothing to do with steering feel.
For the most part you have sufficient flow from the pump if you can make very quick steering wheel motions (such as trying to evade something that suddenly came in front of your car while driving down the road.) If you do not have sufficient flow, you will feel an abrupt increase in steering wheel effort as you try to whip the steering wheel. You can test for sufficient flow by finding a large, empty, parking lot and driving in a straight line at about 15 to 20 mph. Suddenly whip the steering wheel as if avoiding something in the roadway. If you have full assist during this maneuver, you have sufficient flow.
When there is not sufficient flow some people have incorrectly described the abrupt increase in effort as having their steering "lock-up" during that maneuver. It did not lock-up, what you are feeling is the lack of fluid flow to move the piston inside your steering gear (or the assist cylinder on C2/C3 Corvettes) quickly enough for you to make the evasive maneuver.
I do not recommend external by-pass fittings or external components that claim to reduce flow. They cause the pump to continually work against the back pressure caused by the needle valve in the unit. This will cause increased power steering pump operating temperatures. The production pump discharge fitting causes internal recirculation of excess oil and does not increase system working pressures.