hi all I'm new to this to bear with me, i have a mk2 fiesta popular, and the engine is slowly dying on me

, i have recently bought a 1800 zetec out of a gti as well as many other parts including the full car wiring loom,edu and main fuse box.
Now reading through some zetec conversion threads i have found some wiring diagrams which showed you use only some of the wires on the loom, but the wiring diagrams have nit been much help, I'm still stuck and i want to cut the loom and get that side of the conversion ready before i start to fit the new engine. if anyone has some advice it would be much appreciated, Thanks Royce