Seems like I read that they are interchangeable - just take it to your car, hold it up next to your current pr, and see if it will install. I remember now reading that the larger fpr common in the older cars will work on a '93 940 which has the smaller fpr.

This is from the 740/940 FAQ:

Pressure Test: Specifications.

[Jim Holst] The Volvo green manual states that the system fuel pressure for Bosch, Regina, non-turbo, and turbo 4-cylinder B2XX and 6-cyclinder B6304 engines should be 43.5 +/- 1.5 psi (or 300 kPa) static pressure. The rail pressure should be 43.5 minus the vacuum tester vacuum at the regulator vacuum port. This tells if the regulator is working. Residual or shut-off pressure should drop below 29 psi (200 kPa) in less than 20 minutes but not too quickly which could mean leaking injection and cold start valves. Note that system components among Bosch, Regina, and Motronic are NOT the same: the part numbers and specifications differ.

Bosch Systems:

With engine at warm idle, FPR vac hose removed and plugged (simulating Wide Open Throttle/accelerating condition) pressure should be 43.5psi.
With FPR vac hose reconnected, idling fuel pressure should be about 36.5 psi.
Regina Systems:

With engine off, the pump hot-wired at the fuel injection relay and FPR vac hose removed and plugged, pressure at the rail should be 43.5 psi. That makes it the equivalent of Wide Open Throttle, but with the FPReg feeling atmospheric pressure, rather than the normal vacuum of a running engine