Yes, if you can get the 360 to recognize the drive, that's great, you can reformat it. However, I do not believe the 360 won't touch the sectors that you've flashed HDSS.bin to, so the drive will still have the generic security sectors (hdss.bin).
You can easily use the generic HDSS.bin from the internets from another 120GB hard drive, but taking it online is going to be risky. You could try to find a friend with a 120GB official drive and ask to get his HDSS.bin. That might put both of you at risk if you both go on live at the same time, but it can't be any worse than using the generic one.
Your best bet is to crack open your hard drive and hook it up directly to your PC with a SATA cable. Then use HDDHacker to try to dump your security sector into your own HDSS.bin
If you can do that sucessfully, you can use HDDHacker to rebuild the drive from scratch. I've not used the program myself, so you'll have to find some generic tutorials and figure the process out for yourself. If HDDHacker is unable to find your security sectors, then you're right, the program crashing did wipe the drive. If this is the case your only option is to buy a new hard drive or get the HDSS.bin from the internets or some other 120GB hard drive.