First of all, a 'compression test' without a dry reading versus a 'wet' (a wee bit of oil dumped into the combustion chamber) is next to worthless .... WHAT were the compression values or does this require an additional charge for such an answer? WHAT was the engine temperature when the 'readings' were taken? When was the compression gage last 'calibrated' ???????
A 'dry' reading will indicate the integrity of the head/valves; a 'wet' reading will show the integrity of the piston rings, etc.
That your marina didnt report such would make me VERY suspicious that they are simply looking to do a 'replacement' ($$$$$$$$).
If the cylinder pressure are 'equal', the engine is still 'operable'.
Id strongly suggest that you get yourself a compression gage and learn to do such simple testing. yourself .... (wet and dry). NAPA and other national, etc. 'auto stores' sell compression gages at very reasonable cost ... and they come with 'instructions'.
Go to Moyer Marine Atomic 4 Engine Rebuilding and Parts
and join the forum there. Also you can purchase Don Moyer's "Atomic-4 ... Rebuild and Maintenance Manual" ... and save yourself a fortune when dealing with 'marinas' looking to do unneeded work at well beyond outrageous prices- and to better guard yourself from unscrupulous 'shysters'.