If you are looking to use a scuba regulator or tank for something other than scuba, like running an airbrush etc, you need to understand the tank valve has nothing to do with the pressure coming out - all scuba valves are designed to maximize flow and pressure.
The regulator itself is what determines the pressure of the intermediate air from the regulator. Nearly all regulators are two stage with the first stage attached to the tank reducing the air pressure to around 110-145 psi depending on the model and how it is adjusted.
On some models the intermediate pressure is only adjustable internally with the addition or substraction of shims under the main spring or by replacement of the spring. Others are externally adjustable.
I have a US divers Conshelf XII first stage that offers easy external adjustment and can be adjusted down to as low as 10 psi. It's great for airbrushing, inflating tires, beach toys etc. Scuba air is hard to beat for airbrushing as it is very clean and very dry.
The Conshelf XII is an old first stage offerring only 2 LP ports and 1 HP port and not very useful for diving. You may be able to find one on e-bay for around $25.00. Or check your local dive shop, they often have a box of outdated equipment they will sell for non scuba related purposes. With the addition of a low pressure inflator hose and a fitting to allow you to attach 1/4 NPT threaded tools, hoses and adapters, you can do just about anything with one.