No plans to replace the harness unless we encounter something unexpected. We have not thoroughly investigated it yet, but there does not appear to be any obvious problems.
Before the motor goes back in, gently cut the stock loom off and run your thumb up each wire in the engine bay to check for slits, corrosion, or rodent chewing. If everything looks good, you can get new loom tape and rewrap it.
Also, you may to consider the MAD bypass method. It's cheap insurance if you're going to keep the stock harness. I would highly recommend at least looking into it.
I almost lost my old 70' Nova to a 12v constant wire that was shorting against the metal dashboard. It caught the insulation on fire when we were driving it. Thank God I brought an extinguisher with us that day. Ever since then, I've been somewhat neurotic about wiring and promote risk management with electrical.