I do exactly what you are proposing with porters and stouts. I use bourbon, instead of scotch, and recently used rum.
If you can, put the chips into a bag when you add them to the beer and tie it off so you can pull it out. Taste it every so often to see when you hit the oak level you want and then pull out the bag.
Alternatively, you could just add the scotch that has been oaked. I typically add both the oaky bourbon and the chips.