Yeah, i had a look at the bynorm and GA spares catalogue and couldn't find anything remotely similar. Although from your pics its hard to tell what's wrong with the blade.
Retrofitting is not a problem but there are 2 main things to consider, cutting width and how high up the pan the new assembly will sit. We need to see the boss to see if it has a deep spacing or a shallow one. Judging by the 2 bolts in your photo i'd say at least 10-15mm beyond the bottom of the crank.
Also helps to know if the crank has 1 or 2 keyway slots as that will help eliminate the types of bosses we can and can't use.
