Keeping the golden rule of salt water in mind (if it ain't running it's rotting) I would prefer the 2yr old motor with 300 hours.

One of the local PD's had 502 powered Scarabs that would run anywhere from 3,000 to 5,000 on a set of engines.

Happy New Years,
RB

Remember, stock bbc 454/502 require a top end rebuild at every 250-350hrs, that's approx. $2500. 500-600hrs require bottom end, that's not cheap, so consider the hours and ask if top and bottom rebuilds where done timely. 496 is different, and a lot more stout, I think it's 800hrs for the first rebuild.

Good Luck

Who said it was worse? I said that 300 hours in 2 years is bad compared to 300 hours over 10 years and by bad I didn't mean that the motor is "bad" just referring to it having a lot of use in a shorter period of time. I've taken my boat out almost every weekend since I bought it in June and I still haven't put 30 hours on it yet so to me someone that puts 100+ hours in a year is a lot. That's just my opinion but opinions are like azzholes, everybody has one!

Not everyone is running in saltwater though.

That is a requirement for a box stock Mercruiser 454 or 502 ? Probably the most overlooked maintenance requirement in the marine industry.
ed

You did. Post #3 in this thread.

I put 150+ hrs a year on my boat, as anyone who has owned boats know the more you use them the better everything stays working. The worst thing for a boat is to sit unused. In south florida we boat year round. Any stock engine outboard, I/O ect that isn't a HP model will easily run for 2000 hours if it is maintained properly. As somebody else said the hours are nearly meaningless on a used boat condition is what is important, that is especially true of an older boat running a 454MPI or 502 ect. A survey and engine inspection are the best options.

And your comment about the diesel truck is wrong also, a two year old truck with 300k miles means the thing was driven on the highway almost exclusively and will have very little wear and tear compared to a 10 year old truck with 300k miles. Like you said just my opinion.

At 600 hours my main concerns would be how hard the engines were normally run and if regular maintenance was performed. If the previous owners ran the boat conservatively, and if the engines had regular maintenance performed (documented maintenance history), and the numbers on your engine survey look good, you should be fine. Otherwise, run Forest run!

not on a black engine maybe blue

I could not agree with this more - boats were meant to be used. When they sit around collecting dust things begin to deteriorate. I would not be concerned with a well used, well maintained motor. As said several times above, get a survey!