Actually, if he buys another MFM drive, I think we can both bet that it won't be formatted for a Mac XL so since the current hard drive is "no good" on the Lisa, it's worth a shot just to see if the drive is good at all.  If it can be low level formatted, than it's like putting in another MFM drive in; you just don't have to buy it first.   It's useless right now so there's no loss.