90 would be OK if both were that. And yes they should be within 10%. Has the motor sat for a long time without being ran? If so, soak the low cylinder with PB Blaster or any good penetrating oil. The best according to a test done by a machine shop (and cheapest) is a 1:1 mixture of ATF and Acetone. Let it soak for several days then run the motor for a while and then recheck the compression. What happens is when the motor sits for a long time with 1 cylinder at the top of its stroke the rings stick causing low compression. Soaking it with penetrating oil frees the rings and restores compression. No guarantees but I have seen this work.