Re: Looking for advice on a plan of attack (regression).
You need not waste the full depth frames. If they are plastic and you have access to a table saw, just shake the bees off the frame, then cut the bottom off with the saw to make it 3/4 depth.
For your natural combs just feed them in between the built combs so the bees will build them straight. Do this gradually so you do not over extend the bees or spread the bees too thin. That's if you want natural sized cells. But if you want to regress the bees to 4.9, that is going to take a lot more work.
44 years, been commercial, outfits up to 4000 hives, now 120 hives and 200 nucs as a hobby, selling bees. T (mostly).