I use a regulator to check pressure in a shock, they go up to 500 psi or so.
But remember you consequently lose the amount of nitrogen that flows into the hose and regulator in the act of checking pressure.
IF you have a bottle or access to a bottle of Nitrogen, All you need is a regulator and an air chuck rated to 150 psi or more. The common air chuck is not rated for over 90 psi, I don't recommend it.
Set the regulators output to 100 psi, hook up the chuck to the shock, let the pressures balance, crank the regulator to the desired pressure (130-180 psi). remove the air chuck from the shock. Done deal.
Nitrogen is an inert gas and is fairly cheap because 70% of the air you breathe is Nitrogen.
-BIG DAN