Well, I've been through this before. Example, you get the boat in the water, find a leak in one or both of the lower units....next thing you know your doing a boot job or worse yet a steering shaft pin job which is labor intensive, expensive and requires a rebuild of the transom assembly. You have 2 lower units, better fix both and I spent $1500 to have 1 lower unit completely done. I already see where the lower units are roped to the swim platform. Cylinders/pumps ok?
The gas tank is "dirty". You will need to probably pull the tank and have it steam cleaned. That's a few hundred bucks right there. Can you pull the tank without pulling the engines? If not, the engines come out along with the gas tank. Now you need new fuel hoses to the gas tanks. I spent $100 for a 5ft piece of hose....just saying.
Wiring ok? Motors have good compression? Spot any cracks in the exhaust manifolds? Fuel lines should be replaced and carbs pulled, hot tanked and rebuilt.
See where I'm going with this? And you have not yet addressed the steering systems, trim tabs, broken this/broken that, battery systems, not to mention cosmetic stuff like reupholstery, cushions, wood, etc etc.
Just saying, she's a 1975 that has not run in a long time. Don't go about this thinking you can buy a 25ft boat for $900 and get out of this cheaply. There is a reason it's $900 and not $7000 or so.
Like I said, I've been there and I've done that. If you are up for the challenge great! That boat should have "good bones" to work with. However, you better have some funds set aside to get this thing ready for the water.
I bought an 88 Sundancer with "good bones". Then found the rotten transom and stringers. Many thousands later, I have a rebuilt boat, rebuilt 454 and rebuilt lower unit. Don't get me wrong, I love the boat and know the ole girl inside and out now. I had the funds to do the project and I'm glad I did it.
Just don't go into a project like this with blinders on.