I've been doing a lot of ferryings of planes that have had questionable mechanical states the past few years. The following has managed to not get me killed.
1) Do a thorough pre-flight. Very thorough. Assume the mechanics are trying to kill you.
2) Pick a good weather day. Clear and a million is preferable. You want to stay in VMC at all times and assume the instruments are going to try to kill you.
3) Do a couple laps around the airport at altitude (not T&Gs) before you leave the area. Watch oil pressure.
4) Fly IFR if it's reasonable to do so and you are appropriately rated. Otherwise, get flight following.
5) Carry a 406 PLB.
6) Land after one hour, preferably at an airport with good services. Check the oil and do a thorough walk-around.
7) Carry a notepad to write up squawks you find on the plane (you will find them).
8) Make sure your path takes you near good airports along the way. Know where some of them are.
I realize this plane should be in good mechanical state, but you still shouldn't trust it since it's new to you and your friend.
Skill wise, if you can fly a 172, you can fly a 150. I wouldn't worry about that one bit.