I have a decent working HUD at this point, and permission from the original author to share it. I will post a beta version to this thread for you guys to try out in the next couple of days.
I started looking into the issue of the non-working gauges and the nav radio. I'm totally new to this stuff and just learning as I go. As far as the gauges go, I noticed that the Stargate Cobra's aircraft.cfg file defines the engines as engine_type = 5, which is a turbo-prop. The AlphaSim Cobra, on the other hand, defines the engine_type as 3, which is "Helo-turbine". I didn't have time, but later I will change the Stargate Cobra to type 3 to see if/what that might change. I looked through the actual gauges themselves, but didn't notice anything that looked incorrect. Again, I'm totally new to this, so someone who knows what they're doing might want to take a look as well.
I also noticed the AlphaSim Cobra defines just one engine, and just duplicates the gauge readings. That could be another option to try for the Stargate Cobra. It may get the gauges to look right, but I have no idea what else it actually affects.
I haven't seen anything obvious with the nav radio yet.
As far as the electrical issue goes, there are quite a few values different between the Stargate and Alphasim versions. I noticed Stargate has generator_alternator_voltage=26, where AlphaSim has 28 (which I think is what it usually is supposed to be). Changing that value might be worth a try, plus all the AlphaSim systems seem to have a much lower MaxAmpLoad value (3 or 5 instead of 15 or 20). I'm not sure if that is the max amps that particular system can handle, or the max amps that that system will draw. To top it all off, AlphaSim has electric_always_available = 1, which means that system may not work and it just needs to be told to be on at all times...
Like I said, I'm totally new to this and kind of having fun digging in and learning. But if someone who knows more wants to take a stab at things or point me in the right places to look, it would be appreciated.