Have you tried your local import parts store or even GenericAuto? I've had no trouble getting MetalMasters for our older Volvos at such places, although they might have to order them from the distributor (takes one or two days). They do take a little warming up, but hang in there great once they're hot.

Be sure to specify that you have Girling brakes, not ATE... the 140 brakes are common with 240 brakes through most of production, so pads really shouldn't be hard to find. They're sold under the Repco and Axxis brands (and also another I can't remember) -- doesn't matter which you get; they're identical.