I have installed 2 AAW Harnesses and used weatherpack connectors for almost all terminal ends. I don't care to splice in the old terminals from the original harness.
You can layout the whole original harness and use as a jig for the new harness to get the wire lengths correct.
The only thing I do not like about the AAW harness is that it does not have the Ford Wire Colors. I changed over to the Painless Universal Ford Harness (10123) instead for custom applications.
For the Higher AMP Circuits I add a Blue Sea Safety Hub 150 (Marine Application) that has it's power Direct to the Battery. I install the power wires for Chassis Harness (70A), Alternator (150A), maybe Stereo (100A) and EFI (35A) here.