You've gotta LOT of work ahead of you. We met a guy at Carlisle in 2007 who actually dropped the 'Cuda body over a Viper chassis, heavily modified of course. The interior, steering, suspension, etc - was all Viper, with the body components modified to fit over the frame. It was an absolutely beautiful car.
I agree that you should use a factory Viper harness, and modify it to suit your needs. Let me give you some websites:
forums.viperclub.orgThis is the home of the Viper Club of America - I'm a non-paying member, currently. I'd recommend this resource to help get some detailed information on the Viper engine and it's requirements.
www.xvipers.comwww.x2builders.comThese are salvage Viper sites - possibly a good source for harnesses, misc brackets, parts, etc.
www.ebay.comI'd check here for service manuals for the 04 Viper - this will give you wiring diagrams, technical specs on the engine, even things like torque-specs for motor assembly and installation.
I'd suggest some SERIOUS bracing on the 'Cuda body - those Viper motors put out more torque than most diesel truck engines. You'll twist that body like a pretzel.
I'm slowly developing more Viper contacts every day (just bought my 2000 GTS Coupe) so PM me if you have any questions or problems - I might not know the answer, but I can help you find it.
Jeff