[hemi43]

The first thing you need to install is the transfer case. Everything else is located off of it.
As far as the 4 degrees, this is not a number to just guess at. The engine MUST be the same angle as your pinion angle, and you want around 3-4 degrees of angle in your U-joints.
Oil pan clearance is the reason you can't move the engine too far forward, so make sure your pan is on during mockup.

Install the transfer case, install the rear diff, install the rear driveshaft and the rest will fall into place.

Edit; I just realized you're using an NP241. My info above was if you used the original transfer case and it's factory mounting points.(Not sure why you would use the 241)