You're in luck, we have a wealth of knowledge here about the 327 and 350 Q motors. I think if you'll search around in the MASTER INDEX FILE you'll find some good stuff, and as Mark indicated, he has some great info too. Mark is our resident expert, very much "hands on", with current knowledge and some good buddies who know what they're doing too. You stand to gain a LOT of good tips from him.
One thing in particular you should know about SOON with your new purchase. The generic back yard automotive enthusiast probably won't realize the Q motor is vastly different in many ways from the rest of the small block chevy motors on the planet earth. The cylinder identification and firing order is different, and the intake manifolds are different too. They're GREAT running motors, by the way,
Here I am a few weeks ago, checking one of the several 327 motors in our family. This one is a Q as you can see, and it runs very strong.
Proof of the running condition shown below! This is a 31 like yours.
As far as the "need to rebuild", naturally we'll give you the benefit of the doubt, but those motors may not actually need rebuilding. I recommend you be sure about it first, as you probably already have done. You can not judge the internal integrity of a motor by looking at the paint or the amount of dirt on it. If they don't run well, it may be because you are still running old fashioned contact points, in which case you should change over to the Pertronix magnetic pick-up modules that cost about $70 per motor and take a few minutes to change out. In addition, there are some timing and carb issues that may make a huge difference in the way your motors run. No need to pull a motor if it's something that can be tuned up.
Regards, Paul