I would highly recommend getting two SolSheet X complete kits with a single 320w driver on a split cable to run both in tandem. Perfect for your space, and can be put together with a screwdriver, a utility knife and needle-nose pliers. The kits do all the rest of the heavy lifting - including cabling the driver with a T-splitter and screw-together connectors.
The SolStix arrays require circuit wiring knowledge, soldering and cord splicing skills, and some drilling. Not hard at all, but necessary for success.
As for your color temperature ideas, you are thinking about it correctly. One of the advantages of SolStrips is that they can be combined in different CCT ratios to build a custom spectrum to suit your needs. Your idea of 4x 3500K plus 3x 2700K would give you a blended average CCT of 3157K, a terrific spectrum for a flower space.
Want to replicate your HPS spectrum that's worked so well for you? Go straight 2700K.
Want a little more blue? Combine two 3500K strips with three 2700K strips. Prefer a lot of blue in the flower room to keep those sativa hybrids tamed? Use three 3500K strips with two 5000K strips. Have a clone, veg and/or mother space? Straight 5000K will keep them healthy, fat and squat. Virtually any spectrum that is useful for growing can be created by blending together the three SolStrip CCTs.