Sweet.
So you were able to hear it run for a little bit? And shift into forward and reverse? No undue grinding or clunking?
When they ran it for you, was the outdrive in a bucket of water or did they just run it dry?
How did the steering feel?
There should have been a little plaque with mfg. information- on it it will give the year of manufacture, cargo capacity, etc.. it will also give the gross weight of the boat. Make sure it's something your truck will be able to tow. Does the trailer have brakes (surge or electric)-if so make sure they are not stuck on (unlikely, but it could happen.)
And, like I told you before- if you are sure this is the one, be prepared to spend some money. You will undoubtedly find things to fix the first time you take it out.
If you want, let me know when you are ready for her maiden voyage. I can follow you with our boat just in case. Remember, it's a long swim back to the dock if you break down.
And for god's sakes, once you get it running reliably, LEAVE THE ENGINE ALONE!!
-JP