Talk to Craig Dori in Indy about Wilwood. A few years ago Craig designed and made a new laydown frame and did a lot of work with brakes including some components from Wilwood. I think he had issues and ended up using something different for front calipers (this was a 100cc kart though). I can get you Craig’s contact info if he doesn’t comment in here.
You’re right about the EC-750 front calipers. They are not self adjusting so as pads wear you have to manually adjust by adding/subtracting shims.
FYI – Craig also had new front brake hub/disc carrier set ups made and has some on the shelf. I bought a couple of sets recently, but he has more if anyone needs some. I think he has discs for these but they have the standard MCP bolt pattern so you can bolt on the discs you already have.