From a boat I am considering purchasing, 700 hours, all original twin454 mag efi freshwater boat:
Port engine: 151, 152, 138, 140, 134, 147, 148, 150 Starboard: 150, 127, 140, 134, 128, 150, 140, 140

You are already at the 15% diff between hi and lo that is considered acceptable for runnable. Are the motors priced as rebuildable cores or priced as good ready-to-go engines. in a PC these engines will hold up a while. But the C does, after all stand for Cruiser.

LOL, yeah I got the PC thing. No, this is in a Formula 30' go fast style boat priced a little higher than I think is market. But, he did do a comp test for me, so I thought I would post it up to see what more knowledgeable people figured the state of the motors are. At 700 hours and
those numbers, my GUESS is that it won't be long before I have to have some motor work done.

those motors are expensive cores. worth 1500 each since you are sure they aint blown. cuz the couple of low cyls gonna get lower fast with any full throttle usage. like 5 lbs every sunday....

For having 700 hrs, those CR numbers are not bad at all. A couple are a little low. A leak down test would give a little more insight.
Most likely could use a valve job/head gaskets in the future. The future could be anywhere from 10 to 500hrs though.

If not leak down testing for whatever reason -

for the lower comp # cylinders -- put some 50 w motor oil down the cylinders s - turn motor over by hand slowly a few revolutions then go back to comp testing. See what the # s are then. If the numbers Improve - its cylinder / ring / piston wear.

Also warm up engine and do running vacuum testing.

So if numbers don't improve, you got a chance with valves...

and springs

So, basically, it's what I thought. Plan for some future engine work. Better get a DEAL on this boat to compensate for the anticipated engine work in the future since it won't be cheap. And, right now, this boat is not a DEAL. It's all the money for what it is, especially considering
the future engine work. Story of my new boat search so far.....NEXT.....

If he takes 10 off for motors, consider it. Cuz you will get a year while you get 2 more motors together.