What brand of press? Dake? K R Wilson? OTC?
You won't find generic pressure gauges with tonnage markings on them, no real demand. Only way to get one will probably be from the manufacturer.
With Dake, hold on to your wallet, they are pricey. Wilson is out of business, but made an excellent press, I'd gladly trade my 25 ton Dake for a comparable K R Wilson.
You could take a standard pressure gauge and calculate the tonnage at various pressures and paint mark the gauge glass.
Charles