02 MXZ fuel pump rebuild kit

I have a few of these early 2000's mikuni fuel pumps that im trying to find rebuild kits for. They are almost identical to the Mikuni MK-DF52-531, but these ones have a taller cylinder at the back of the pump. I cracked one open and looked inside, the MK-DF52-531 kits will not fit. The anatomy is entirely different (there is a thick plastic gasket sandwiched by two rubber gaskets connected through the plastic one by a metal plunger. the spring is also significantly longer). Does anyone know where to find rebuild kits?
thanks
-Alex

02 MXZ fuel pump rebuild kit