Wow, those guys took it to a level that I don't know I'd be going to. Pretty slick.
Id be very interested in knowing what the difference between the 2 actually is. If it's only width it could be modded to fit but with that price tag i'd be hard pressed to cut one up.
If you've got two original K members or cars to measure, you could check.
I've got a spare K that I'm going to use for a suspension swap, when I rebuild the front end on the Scamp. I could pattern it.
If I got the material for this K member and it turns out nice, I wouldn't mind building a jig to make factory appearing aluminum K members for an A body.