Replacing logic board HELP

Hi, if I want to replace my the logic board in my Seagate Barracuda 7200.7 hard drive, what information do I need to match to buy a workable replacement?

For example: the model #, the P/N, firmware, and the PCB #

Out of those, which ones are the most important that I need to match?

If the specifications of the HD is exactly the same, but the PCB# is different, would the logic board still work? What about the opposite (PCB# is the same but the HD isn't exactly except that it is a Seagate)?

Thanks, any help would be appreciated because I am just lost and I really want to recover the data on my HD!!

The same pcb is important. The same firmware? It would be important if you got ahold of an old one and the newer one fixed a critical error. I'm also assuming there is no data on this drive. If there is then everything being exact would i believe be vary important.

Just curious do you have a clean room to do this? or do you plan on destroying your hard drive?

Thanks for the replies.

@Kbits: The computer repair store I went to said that replacing the logic board MIGHT recover my data on the HD; he wasn't positive though, but it was either this or spend hundreds of dollars on a professional data recovery service, so I decided to try this first.

@EnFoRceR22: I won't be doing the replacing, a computer tech will and he's done it before so I'm sure he will do it properly. Also, when you say the PCB is important, is this from experience or websearch/general knowledge? The reason I ask is because I found the same exact HD on ebay, but the PCB is off and I don't know whether or not I should get it...

@nukemaster: Thanks for the link, it is very useful.

Does anyone know if the PCB has to be the same? As I noted above, I found the same exact HD on ebay (same model, firmware, p/n) but with a different PCB so idk if it would work or not..

If you've had experience replacing the logic board (success or failure), could you post and describe what specs were matching when you did so? Thanks!!