If you have boxes with bees all the way across, you might be able to meet the six nucs goal alright. But, I would order queens to make the nucs with. When I have a mean or winter overeater, I break it into nucs of three frames of brood in each and give that split a caged queen. I do not know what you are using for equipment to make those nucs. I use a router and make a 3/8" channel thru the middle of a deep box the same depth as the frame rest and put in a plywood wall that is level with top and bottom and tightly divides the box. I shake the bees off frames of brood for nucs and put three frames in the center side of each, put a flat metal or plastic queen excluder over the donor hive and put a caged queen in each side. If I have killed the queen left in the bottom I give that group a caged queen also. Nurse bees come up thru the excluder and cover the brood above. If the weather is warm I put an excluder over the brood box and put a super under the nuc above. If it is cold, I wait for a day until the brood is covered before putting the super in between.
If the splits were strong enough and the spring flow hits in force or main flow, I put an excluder over the divided double box and the nuc will often store some honey. When I was expanding rapidly, I often put on a deep box of foundation and let the double draw the foundation above and fill it with honey. They I would extract that box or boxes and put a divided box on top or in your case, two nuc boxes with drawn comb and feed it full with syrup as I would take the main flow honey crop instead of letting the bees fill the second level with honey.
My bottom boards for the divided deep is a rim of 1/4" 1 by glued and stapled to half inch plywood with a center divider to keep queens apart and an entrance for each unit on opposite ends. I cut 1"slices of scrap 2"by ? for the bottom feet/runners whatever you call what keeps them off the ground. I have been doing variations on this theme for years. The colonies store surplus or mountain camp winter feed thru a queen excluder with no aggression.
Having the second story as separate boxes is highly desirable. I run these divided doubles but it is an added level of difficulty you don't want if you have room for another stack of specialized equipment.