I spent quite a bit of time on this issue myself. I wanted GPS functioning "in-panel" in the 2d and vc, as well as a drop down; and you're right the multiple panel files in the Aeroworx King Air can be a bit intimidating.
I started out installing the default GPS in place of the WXR. After many differerent versions I finally found the Friendly Panels - GPS Pack. (Its available here in the fs pilot shop at a very reasonable price. I use it on just about all of my aircraft now)
I now have the GNS 430 mounted in panel and functioning in place of the KLN90b and the GNS 530 in place of the WXR. I like the combination very much and as far as I can tell the functions in both the EFIS and analogue cockpits all work fine. I mostly fly in the analogue cockpit.
I would be happy to share the files with you or anyone else interested, although I have never shared files before and don't really know quite how to go about that. I don't think there are any copyright or other legal problems but I'm really not sure.
Alternatively I would also be happy to offer any guidance through the process if you would like.
Good Luck with however you decide to proceed!!
Jesse Cochran "JesC"
"...eyes ever turned skyward."
Alienware Aurora R4, Win7x64, Intel i7-3820 @ 3.6ghz/4.3ghz turbo, 8gb RAM @ 2133hz,
Nvidia GeForce GTX580 @1.5gb, 1TB SATA @ 6gb/s, Intel 330 120gb SSD for FSX