Speaking of which. OP look up "Young Performance Marine" on Fakebook. There was just relevant discussion a few months ago from him.

I am well aware of this. and currently have a quote for parts and labor. Didnt have the resources to do it this winter, but will be pulling the engine and taking it to my engine guy in Wisconsin next winter. The person we bought this boat from didnt run it hard. Not sure that matters, but hoping it will help me get through this season. Also going to have him test the headers while the engine is out.

I saw this a while back and sent it to my engine guy. He agreed it does need to be done, but will have to wait until next winter unfortunately.

As far as the hours go, it doesn't matter if 200 of them are at idle, they are still hours the motor has ran. I hope you an make it to next winter to do the engine work, but if something goes wrong this summer it'll be way more to fix it then. If you do a complete rebuild and the tope ends are refreshed correctly, then you can go 500hrs easily.

I would disagree with that. One hour at 5000+ rpms rotates the engine internals 7-8 times more and under a much heavier load than one hour at idle.

agreed. I’ll take an engine idling for 499 hours with 1 hour operational vs 499 hours at 5,000 rpm.

I guess I should have been more specific on that. If it is the original factory Mercury parts in the heads I wouldn't trust them 200 hrs at idle. That's a personal opinion from seeing quite a few that have came apart with low hours.

I have read through all of that Young Performance facebook page and agree with your concerns. We have 2 younger kids so we wont get out on the lake much this year. I know it only takes one time out to finish the engine off, but going to take the risk. We will only be doing the Harbor hop in the spring and then going to the LOTO shootout in Aug. There will be a couple of weekends that we get out on our local lake and that is just out to party cove and back which wont put many hours on the engine.

As of now, here is the updated list
Oil
Oil Filter
Spark plugs
Fuel filter
Impeller
Drive oil
grease engine coupler
grease gimbal bearing
replace inline fuel filter
pray for the top end to hold together

370 hours is borrowed time. That’s about when we refreshed our 500’s.

new lifters, valves, rockers, springs, push rods, etc

Next thing to worry about, I assume it has an XR drive on it, has it been apart?

Getting 370 hours on an upper gear set is not normal