Abandoned Ship

me and my buddy successfully swapped out his y5 head for a y8, and ran into timing issues which will be sorted out later (car is sitting don't fret) but my question is the ECU. The HX(p2m? p2l?) is twice the size of the the ex(p2p) and they dont plug in the same. on the p2p the far right plug is not used, and has no pins, but the 2nd(maybe 3rd its not infront of me) is not used on the HX ecu. does anyone have any idea what to do?

and please leave out the y5 vs y8 head arguement.

thanks in advance, pm please.