I saw a 2007 30 hp mercury 4-stroke outboard for sale, in the description it says all 3 cylinders compression read 70 psi. I contacted the seller and they told me that there is no spec PSI range listed by them manufacturer, only that the cylinders be within 15 % of each other. I have searched everywhere for more information but I cannot determine if this is an acceptable compression. Does 70 PSI on all 3 cylinders indicate a good running outboard? I appreciate any insight. Thanks.