I've had some time to take a look at everything and I am reasonably sure I can do this myself.
First, the PAC unit... It looks like I can just use the harness and discard the converter. I can clip the connector off of the harness and use the amp's speaker level inputs. As a bonus the amp's speaker inputs are signal-sensing so the remote power-on is not needed, which means one less wire to run (a small bonus)
Once i get the power from the battery through the firewall (I found a couple of very clear tutorials going through the passenger fender well) running the power and speaker wiring though the passenger compartment to the trunk looks like a piece of cake.
I've also found in the same tutorials removal steps for access to the shaker 500 head unit, which also looks pretty simple: remove the shifter trim, cup holders and face plate...done. The PAC will make the wiring plug and play.
The clips used to attach interior parts are 1000x more durable than the practiically disposable / guaranteed-to-break crap of the 70s and 80s.
All that is left is determining a physical mounting location, which right now I am simply looking at mounting on a board to the underside of the rear shelf, between the speakers. It has cooling fans so an upside down orientation should be ok.
Wondering if I can even used HD Velcro to mount to the rear shelf?... Hmm.
2011 Mustang 3.7L V6 Premium ∙ MCA (203A)
Ingot Silver ∙ Charcoal Black ∙ Auto
HIDs ∙ Security ∙ Comfort Package ∙ Remote Start
Koni STR.T shocks/struts ∙ Roush DUB springs