What are your plans? Is it going to be just something to go out and have fun in?
Are you immune to the "speed bug"? If you're going to want to go fast, go chevy or ford.
If the hull is solid, you could always swap out the Olds later. But, it's not a direct swap.
I have an Olds and wish it was a Chevy. I just don't use the boat enough to justify the money for the swap.
If you're just wanting to get on the water and have fun, a stock Olds can be a great,realiable engine.
Like the guys said, we need more info.
What kind of hull? What condition? If you don't mind, price? What does it need?
Is there a link?
Good luck.