A couple of questions. What will be the use case for the 274 (mesh, client access, etc) and how far of a distance are you looking to accomplish?
It is not recommended to use multiple cables connected together, as each connector pair adds 0.5-1dB of loss. It would be best to source a single cable to meet your length requirements, which can be purchased from any reputable RF equipment provider (Anoison, Ventev/Terrawave, L-Com, etc).
You would just need a 12m N-Male to N-Male connectorized antenna cable, and it really should be LMR-400 at a minimum. The cable and connectors will add about 5dB of loss, which will cut your coverage distance for clients or your mesh range in half (more or less). The 274, for the best performance, should be mounted outdoors with the antenna using the smallest antenna cables possible.