Dude, this is AMAZING! You really seem to have a knack for making accurate beta content. Thanks for taking my suggestion into consideration.
Most of the model looks spot on, but there are a couple of improvements I would make. For one, I would tone down the orange in the rear where the rotor is, maybe make it a tad more pale (then again, this might just be the lack of lighting in the render that makes it look that way). Secondly, maybe adjust the cord(?) on the underbelly, as it seems slightly off how it looks in the screenshot (honestly yours looks kinda jagged). Lastly, and this one is just a personal preference but I think it would be a nice detail; add the "2u-C17" on the side of the rotor as well as the little logo on the middle part like in the concept art (or include an alternate skin for that). Also I feel the need to point out that that thingy on the underside between the two small bug-eyes and the mid-section is supposed to be more round shape with several small individual lights on the front, instead of the glowing intake hole. This is seen on the e3 model upon closer inspection, and the concept art shows this in greater detail.
Looks great so far!
Also regarding the beta jalopy's remake, I haven't been able to find any recent updates on it, which kinda sucks. It looks so fun to drive! That wasteland zombie remake looks cool too. Hopefully that see's the light of day.
I'm currently trying to headhack models and I'm also running into rigging issues so I'm afraid I can't be much help with that. There is a Valve Cut Content thread on Facepunch, I could post about this there and maybe one of them could help you with the rigging issues.
Here's nice close-up from one of the HL2 E3 trailers, in case you didn't know https://www.youtube.com/watch?v=6oQ1sXfVdBc I'm honestly surprised, that Combine Overwiki don't have any screenshots of an old E3 gunship
Awesome, can't wait to see this! Also I would recommend to include the sounds from the leak. For myself, I managed to get that to work by using the script file for the sounds since I thought they had different names or there were a different number of sound files for it.