yes you can use a compression tester, you should also turn over the engine several times if you are just flipping by hand, it will usually take several flips before the gauge stops climbing. Choke engine to get the cylinders a bit wet before you sftart taking readings, this will give a more accurate indication.

The numbers you see will vary from engine type to engine type, some types will show as low at 70-80 pounds and some will show 120 or more pounds, the most important thing is that if you have another engine of the same kind that runs well to compare the readings with. A variation of 10 pounds between similar engines is not unusual, a hot engine will usually show lower numbers than a cold engine.

You may find that if you flip the engine backwards compression readings will be higher, this is not unusual with ringed engines. If you notice higher readings flipping backwards then compare both engines this way.