HI & welcome: That looks quite a shunt has been classed as a write off by the insurance company & if so what class? or have you purchased it for repair ? Firstly id get it on a jig to see if its straight as the strenghtening beams look like they may have been impaired.
Secondly you will want more than 1/4 panel thats a complete side & corner & you will be better of buying new parts rather than cut from a secondhand motor of which you will find hard to find & expensive if you do find one.
Good luck
