Each map is going to be loaded separately into MCEdit, running the correct server version for the original generation. Then all the chunks will be loaded in order to fill in the area, and all maps will be expanded into squares of the same size (whichever map is biggest, they will all be the same). Then they will be all loaded into a 1.7 version of MCEdit, and placed next to each other in one world. I will then smooth out the borders using VoxelSniper. Finally, WorldGuard will be used to "section off" each individual region, and deny building rights to players who didn't play on those maps; as well as provide a border on the world.