I am 99.9% sure it is not a bolt in project. The 250 will be longer than what you have and bellhousing has a different bolt pattern. The 250 can take a little more rpm and parts may be a bit cheaper when rebuilding. If the 250 has a intake cast in to the head (one piece unit) I would avoid it. They are prone to heat cracks and leaks. You can replace it with a older head and intake and still have a good motor. If going to the trouble of swapping, go for a 292, cubic inches rule! It won't cost any more to swap it in as it will the 250, plus it will have way more torque and horsepower. Joe