What brakes do you anticipate using?
My S&S bike has full length outer housing on the brakes and shifter cables, so quick disconnect cable splitters are impractical. But my Ritchey Breakaway (badged as a Raleigh Grand Prix) came with cable splitters so when I split the frame, I can split the cables by unthreading the splitters. And thread them together later. I do not know if you have them or not since you bought the frame used.
Under the downtube you can see a silver colored cylinder with a black ring on it, that allows the cable to be split by unthreading it. The other one for other shifter cable is behind the downtube, so not visible in the photo.
And same type of splitter under the top tube for rear brake cable.
They are not really needed, as I noted I do not have splitters on my S&S bike. If you do not have them, it takes a bit more time to setup and tear down a bike for packing.
Of you were not aware of them, I wanted to make you aware of them. I got my Raleigh as a complete bike, not frame and fork. Thus, I have no clue what the splitters cost since they came with the package.
Others on this thread might comment more if you are interested in them.
I do not think I asked earlier, did you get the S&S wrench with it? If not, the wrench needs to be the right size for the couplers, as there are different diameters.