When to install wiring harness?

[Alphablue]

Thought I would unofficially poll the hive mind! I am building rebuilding this 1968 with my father, so we have two mechanics and two different opinions of course! Have 1” BL, 2.5” SL and four wheel disk installs done. So enjoy the cartoonish, tall truck, little tires look! No engine or trans in the truck, just the shell. For those of you that have rewired, we have the painless wire kit and debating on the install order, before or after the engine and trans are in? I can see +\- for each way and wondering what most do for the order. Thanks in advance!

 

[DonH]

After engine-tranny install with the dash out.