I found a test gauge/hose/valve kit on Ebay for a good price (under $30 as I remember). Basically you have to hook to the top and bottom chamber fittings on the fuel distributor, and have a switchover valve system to the gauge. Do a search here, but my memory says the pressures are about 75 PSI, with one chamber being about 5 PSI lower than the other - this is the critical measurement, the deltas between the upper/lower chambers. This controls the fuel flow to the injectors. There are some very definitive articles in the archives here on the procedure.

DG