hi,
new to the forum. my first post!
i purchased a cheap boat with a pair of partially dismantled aq151s. i have the option to purchase 2 second hand aq151s fully assembled. however they have low compression as below.

On one engine cylinders 1,2,3,4 are all at 75psi the second engine is cylinder 1: 48psi, cylinder 2: 55psi, cylinder 3: 60psi and cylinder 4: 60psi.

the engines have not been split. compression test was done just before removal. the guy replaced them with aq171s with EFI conversion.
with the even pressures is this mainly common to piston ring wear? the engines have 900 hours. if there is damage/corrosion to the cylinder walls what would be the next step?

one motor has new carbs and the other refurbs. electronic points etc etc.
its appealing as i could pay someone to sort the spare engines while i remove the current engines and get it in the water quicker.
any advice please?
yours appreciatively,