Longshot, but try something:

Disable RAID from the bios and then boot to linux.

I just moved a FakeRaid (bios) array from a windows pc to linux, and I was prepared to format it, when at my amazement, I found out that linux recognized the array and had it available on /dev/dm-0

It also did recognize two more disks as raid which had once been in a striped array on windows but weren't anymore and I had to break the array manually and change partition type to get to access the data.

Beware though that there's a possibility that when you re-enable raid it might not recognize the disks again as an array (I find it unlikely, but you never know)