All passives are 0805

C1 = 10uf

IC1(gate) = SN74LVC1G02DCKRG4

D1 = 1N4148WS-E3-18

R1 = 1K

R2 = 10K

U1(cu383) = SN74CBT3383DW

Cart connector can be found on aliexpress though the edges need to be filed/sanded for perfect fit or you can harvest the connector from the OEM board.

FFC connector I used was a generic 40P 1mm pitch one from RTLECS on aliexpress, any realistically that is 40p 1mm should work.

Ideal size for the FFC is 5cm~ again generic 40p/1mm should work great.

Board thickness should be 1mm, HASL is perfectly fine as the only external rubbing contact that's important is the cart slot.

You can use a wire to bridge S to gnd to force the region switch (semi-permanent conversion) or wire it up to the select button to only change region when select is held and the system is turned on