considering that looks like an MFM/RLL harddisk (2 flatcables....) in the drivebay, then that board is likely its controllor.
The MFM/RLL setup is *the* slowest harddisk setup you could get.
On the psu.... yes you can... you need to set a jumper in the motherboard + adapt the wiring... it's been covered before here, do a search - I can't remember the details
Tom UK
