Ok, Maybe I am missing something, but this is a no brainer to me.
Reddevil, Easy fix.
First, FORGET ABOUT HOTSWAPPING. Unless you want to kill some hard drives.
The first thing you should have done here is backed up your softmod xbox's eeprom. Assuming you did, read on.
Step 1. Back-up your chipped xbox's eeprom and then unlock the HD using configuration magic.
Step 2. Take your eeprom backup from your softmod xbox and open it in live info.
Step 3. Convert it so that it is compatible with your chipped xbox version and then flash this to your chipped xbox making your xbox's "twins". (I would have done this automatically as it is easier IMO than xbhdm)
Step 4. Install the 80gb HD into your chipped xbox and then cold boot slayers.
Step 5. Copy the original 5960 dash files to this 80gig drive making it "Stock" and then lock it using config mag.
Step 6. Put this 80gig HD in your non-chipped xbox, fire it up and softmod from here.
Optional: From here, you can either re-lock your chipped xbox HD and leave them "Twins" or restore your chipped xbox eeprom back-up to it (I would leave them "twins" for future repairs/hd upgrades with ease).