1. I suggest we leave your SSD alone and not try on it. If you want to I would suggest a regular Bootcamp installation later (a non-EFI method).
2. Using a regular non-EFI Bootcamp installation is what should be attempted on the Toshiba drive.
3. If you notice the Toshiba is 1465149168 blocks, but the MBR entry #1 is 4294967295 (2048 Gb = 2TB) which is the MBR limit of 2.2TiB, so both disks have a PMBR at sector 0 to avoid non-GPT aware utilities from manipulating the entire disk.
4. The disk0s4 you saw would have eventually become a Microsoft System Reserved partition of 200 MB and the rest would have become NTFS, if the EFI firmware on the MBP worked. It is an older machine, so the EFI may never fully support a Windows 8 installation. My 13" 2012 MBP also gave me errors similar to yours with a just a single 256GB SSD when an EFI installation was attempted. Later 2013 models have newer EFI firmware, which works. I have it installed as an EFI on a 15" late 2013 rMBP.
This is a working W8.1 EFI installation disk layout form the 15" rMBP. You can see GPT#4 is MSR and GPT #5 is Microsoft Basic Data (you can see the list of partition type GUIDs at http://en.wikipedia.org/wiki/GUID_Partition_Table)
gpt show: /dev/disk0: mediasize=500277790720; sectorsize=512; blocks=977105060
gpt show: /dev/disk0: PMBR at sector 0
gpt show: /dev/disk0: Pri GPT at sector 1
gpt show: /dev/disk0: Sec GPT at sector 977105059
start size index contents
0 1 PMBR
1 1 Pri GPT header
2 32 Pri GPT table
34 6
40 409600 1 GPT part - C12A7328-F81F-11D2-BA4B-00A0C93EC93B
409640 487712920 2 GPT part - 48465300-0000-11AA-AA11-00306543ECAC
488122560 1269536 3 GPT part - 426F6F74-0000-11AA-AA11-00306543ECAC
489392096 32
489392128 262144 4 GPT part - E3C9E316-0B5C-4DB8-817D-F92DF00215AE
489654272 487450624 5 GPT part - EBD0A0A2-B9E5-4433-87C0-68B6B72699C7
977104896 131
977105027 32 Sec GPT table
977105059 1 Sec GPT header
Disk: /dev/disk0 geometry: 60821/255/63 [977105060 sectors]
Signature: 0xAA55
Starting Ending
#: id cyl hd sec - cyl hd sec [ start - size]
------------------------------------------------------------------------
1: EE 1023 254 63 - 1023 254 63 [ 1 - 977105059] <Unknown ID>
2: 00 0 0 0 - 0 0 0 [ 0 - 0] unused
3: 00 0 0 0 - 0 0 0 [ 0 - 0] unused
4: 00 0 0 0 - 0 0 0 [ 0 - 0] unused
5. As a next step, I would recommend a non-EFI installation on the Toshiba first. If that fails, the options are,
a. Remove the SSD from the main bay, leaving the Toshiba in the Optibay and try a single disk non-EFI installation, or,
b. Put the Toshiba in the main bay, install a non-EFI W8 and then physically move the disk to Optibay and test, putting the SSD back in the main bay. the
MBR and GPT will move with the disk and should not have any interference with the SSD.