Fixing existing engine harness or rewire from scratch?

[Minnesota]

I'm building an 87 RX-7 (turbo or N/A haven't picked an engine yet, Manual trans) from basically scratch but have most of the main harness, a hacked up dash harness and a mildly hacked up engine harness (previous owner tried doing a 2JZ swap).

my questions are:
would it be cost effective/reliable to just fix the harnesses i have (just replace the plugs and wires that were cut off), purchase another harness off ebay, classified section, etc. , or start from scratch and build a new harness (i'll elaborate on this in a second)

are new oem style plugs available for purchase or am i going to have to find some off existing harnesses?


elaboration of intent:
project goal: restoration/weekend drift car (short distance driving/track car)
what's getting deleted: Sunroof, stereo and audio wiring, electronic locks (if applicable), flip headlights (going with fixed for reliability and weight savings)
electrical skill level: surface mount soldering, fully capable with digital multi-meter, anal about perfection in finish and performance
I will be carefully removing any wiring regarding the systems i'm getting rid of to make trouble shooting easier long term. Also if i go through the effort of making a harness from scratch i will be making a couple (plug availability permitting) to make the bulk wire purchase worth it.

[Minnesota]

nothing? I got as far as unwrapping all of the engine harness and part of the dash harness. tonight i'm working on unwrapping the rest of the dash harness and labeling wires.

[black rocket]

I. Always believe in good wiring as 20+ year old can't posibly deliver along with reliability factor being questionable. There are good waterproof connectors and make sure to invest in quality wiring and redo at least harness. Good luck!