Haven't the Durangos come with 5.7Ls for several years now? Get one of them and use the chassis and all the wiring is already there. Might be a problem with instruments unless you use the Durango IP.
Bryce

Every electronic device is manufactured with smoke stored deep inside... only a true genius can find a way to set it free. The most terrifying words in the English language are: "I'm from the government and I am here to help!"