4 piston brembos, Master cylinder, proportioning valve confusion.

I haven't seen that piece, cuz I refuse to pay the ridiculous Wilwood prices, nice piece tho.
I have used a similar piece on go-carts, mini drags, maybe find this down there, prob at a farm supply, industial equip.
Good job .
Canadian price, US less 30ish%

https://www.princessauto.com/en/disc-brake-caliper/product/PA0004760161