I am thinking of downgrading my old Fat PS3, after some research i have found what i think is probably the best video tutorial on YouTube, it is detailed and very clear. So if you are interested on downgrading your (Nand) PS3 console thwn watch this video.
Here some links to things you need :
All files needed by UltraNSC You must login or register to view this content.
Here's 360 Clip Solderless Universal TSOP NAND Flash Chip for PS3 i have found and its confirmed as OK by maker of the video You must login or register to view this content.
Here's Teensy++ 2.0 also confirmed OK by maker of the video You must login or register to view this content.