Sadly, I don't think I can replace the 075's with a midbass, the 4355 has a 12 inch mid, does it? If so it won't fit there for sure.
However I may try to place it like mids in the 4312 but then with two woofers.
Changing the 2445 to something else that can go from 300Hz would be the easiest, though I'm unsure how it would sound with the 2395.
I can have a pair of 2204H's for €160, would it be an improvement?