75 GMC sierra classic face lift and conversion to short bed

[sam in vista]

hi guys

i bought 75 long bed fleet side gmc sierra.
i got it as it is
6 cylinder(292ci) ,automatic gear and already face lifted to 81(i think)
the car is out of country and overseas.

my plane is converting to short bed step side and changing the engine to LS1

car has some body work ,need paint and need some new parts.
it doesn't have rust,just little bit in driver floor pan ,but the serious problem is;somebody stole the complete engine wiring after socket,the car had 12 circuit engine wiring and i could not find it yet. i need the color engine wiring diagram.
the other problem is preparing the parts,as i told the car in not in U.S
but i have to do it.
need your technical help for cutting the chassis and all work depend on that.

here is some pictures: