okay im going to help you alot... this is the best advice you can use...
USE THE KA LOWER HARNESS AND SWAP THE SENSOR PLUGS FROM THE SR HARNESS TO THE KA HARNESS!!!!
Now with that said i have not done a s13 lower harness but i have done a few s14 harnesses and they are basically the same, starter, alternator, oil pressure sender, reverse switch, VSS, and power wire to the starter from battery...
S14 Tranny Swap - Electrical Connections - s14
Simone : My 1996 240sx: Lower Harness is done dilli-yo! - s14 w/sr20det redtop
This will give you the idea of what to do, but you should search and try and find some s13 manual swap wiring guide...