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Individual compression gauges vary considerably, so you may or may not have a problem. Either have someone else do another test (with a different gauge) or do one yourself (it's not difficult, and the gauge is not that expensive---$25-40 at Sears, for example) Rule308 had several good tips for getting accurate results. If all the plugs are out, (which they should be) I don't think it's necessary to have a battery charger connected, (assuming your battery is healthy) as the engine spins over very easily. It's a good idea to pull the coil wire from the distributor cap and secure it with the loose end about 1/4" away from a ground (bare metal), so the spark can jump across the gap when you crank it over. This prevents damage to the ignition system, which can occur if there is nowhere for the voltage to go (as there would be if you pulled the coil wire at the coil) Keep your hands away from this area while cranking, unless you like getting zapped.
Position the gauge where you can see it while cranking the engine. Watch it closely while you do so. The needle will move upward with each revolution. Some typical numbers are 90 PSI on the first pulse, 120 on the second, 140 on the third, 150 on the fourth. (the actual numbers may vary due to compression ratio or other factors, but the proportions should be about the same in any case) You want to make a note of each one, and compare them for all the cylinders. The more consistent, the better. Then do it again, with a good squirt of motor oil in each cylinder as you test it. (not too much--you don't want to cause a hydraulic lock--a squirt or two from a trigger type oil can should do) If the numbers are much higher (by 20-25% or more) on the wet test it is an indication of worn rings and/or cylinder walls.
Note to Repairman Jack: As this engine is a turbo, with a relatively low compression ratio of about 8.5:1, the numbers will be a lot lower than those of a healthy B18B, which is 10.5:1
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