On NOR models, 16mb is stored on a NOR flash, and the rest on the hard drive. On NAND models, all the firmware is stored on 2 128mb chips.
You can't transplant NAND/NOR like that. Each console has "personal" data on their flash. If you transplant the whole flash chip, the console will not boot because it cannot decrypt that personal data which is encrypted with a per console key (even if it did, you'd have to transplant the flash from the same model at least).
What you can do however is rewrite the static parts on the 3.60 console, effectively downgrading it to 3.55.
PS3 Slim CECH-3004A 160GB
PS2 Slim SCPH-70004 - FMCB 1.8b