is the blizzard 1260 and the blizzard ppc different?
1260 has 68060. 1260 has 1 SIMM slot, but adding SCSIKit gives you 2nd slot (and SCSI-II obviously). 1260 has no privision for graphics card (it's possible to add one, but you need PCI busboard or some other extra expansion).
BPPC has PowerPC cpu and m68k cpu. Various configurations exist, from slower 603 and 040 combinarions to 240MHz 603 and 50MHz 68060. BPPC can also have SCSI-II controller, but it can't be added later on (so if you need SCSI you must get model with it). All BPPC have two SIMM slots, and possibility to connect BVision graphics card, or GRex PCI-busboard.
what is the best and the most powerful acceraltor card availible
The best card for A1200:
Blizzard PPC 603 240MHz with 68060 50MHz and SCSI-2, with
BVision graphics card (it plugs to the BPPC). You can have 2 x 128MB 72pin SIMMs to it, totalling 256MB memory.
I had this setup, but my Pegasos II G4@1GHz replaced it.
Frankly, even this fastest possible BPPC isn't that impressive these days.