I'm not a data recovery guy, but my understanding is that Samsungs usually don't need a firmware transfer, if the board is a good match.
Hitachis require that you move the NVRAM chip, but not the serial flash, as long as the firmware is matched.
Current Seagates, Maxtors, and WD's all have adaptive information that needs to be transferred.
Maxtors prior to the Seagate acquisition were OK with a straight board swap.
Professional tools such as PC3000 and Salvation Data's HD Doctor can save and restore the EEPROM data, as long as the board has at least some sanity. Otherwise you can use a chip programmer, either in-circuit, or after desoldering the chip.
See
read-write-serial-flash-wdc-logic-boards-t7192.htmlTo help you identify the NVRAM, serial flash, parallel flash, EEPROM, ROM chips, you could consult my HDD IC database:
http://www.users.on.net/~fzabkar/HDD/HDD_ICs.txtWD usually assigns a circuit location with a U12 reference for the "ROMs". If this location is unpopulated, then the ROM data will be internal to the MCU.
If you still can't identify the ROM, then look for an isolated 8-pin chip. Follow its signal traces. If they lead back to the MCU, then it is probably a ROM. Otherwise, if the chip is near a coil or diode, then it is probably the MOSFET or FETKY in a switchmode DC-DC converter, in which case its signal traces will lead to the motor controller chip (eg SMOOTH).