Just a thought, with the increase in power, the increase in weight and the increase in tyre diameter, wont the brakes need upgrading as well to pass engineering?
With the initial build keeping everything else stock I would also think will go against you in engineering, as I would not have thought the stock axles etc were designed with the power output of the 6.4L hemi...
I would be finding yourself an engineer now, and become a very good friend of his and ask him what he needs you to do to make it pass. My brother does a lot of upgrades and runs the mods past the engineer first, bouncing ideas back and forth until its all designed, then goes and builds it (last build he did was a holden 253 and 5 speed into a shorty patrol with a 6 inch lift. He was told it couldnt be done, after driving it up the trails and using it as a beach recovery vehicle for a while he ended up with a few orders !!
Very interested in watching this one!