they do a 100psi guage for about the same price
http://www.ebay.co.uk/itm/Fuel-Pressure-Gauge-Tester-100-psi-0-7Barg-Jubilees-/170839694516?pt=UK_Diagnostic_Tools_Equipment&hash=item27c6d6dcb4
But as it doesnt come with any female adapters I think you would have trouble fitting it to the male M12x1.5 test port on the fuel rail.
you would also need something like this
http://www.ebay.co.uk/itm/Metric-Conical-Hose-Tail-Fitting-Diesel-Petrol-Oil-Cooler-Tube-Pipe-Fuel-Filter-/280792554118?pt=LH_DefaultDomain_3&var=&hash=item870e66f599
Wait... just realised its designed to be installed by cutting the fuel line so you probbaly wont need that m12 adapter. Although im not sure how well it will work as it would have to be installed before the fuel dampener?
I still think your better off getting an m12 female adapter with a guage on the end and connecting directly to the fuel line.