The 250 and 300 block had more failures than they should have. They are kind of a white elephant on the used market.
The boats for sale with them are generally discounted with the thought that if you need to buy a new motor you've at least bought the boat at a good price.
When/if it blows up put a zuki 300 on there. Some like twin yamaha 150s.
BTW, welcome to the forum!