Mike, thank you for the clarification.
stuboyle, most tool air tanks are capable of 120 psi or higher. It is best that you don't fill it above 80 psi for safety margin if you want to use an 100 psi airbrush regulator.
Usually, you need a dual gauges air tank regulator for fine adjustment. You can find them in most hardware stores including Lowes and Home Depot for about $100.