Panasonic G7 has amazing 4k quality at about 500.00 and you would still have options for a decent lens. I owned one before upgrading to the gh5 but I was not disappointed at all with the images coming out of the G7. Also, go G85 if you need in camera stabilization. Good luck!
Wow I had the same dilemma that you are facing a couple weeks ago. I shoot mainly music videos and show events and needed a pretty decent low light camera. I love the sony A7SII footage I have been seeing online for low light situations. However, I came across one Panasonic Gh5 in store at Best Buy and had to give it a try. All that I can say is that I'm totally blown away with this camera. The build quality is very sturdy. It simply has more than 2 grand worth of features and the image is amazing. I normally shoot with my Red Dragon but this Gh5 camera hasn't disappointed me yet. I use the sigma art 18-35mm 1.8 lens with speed booster and even it low lights this camera is great! Also, in body Image stabilization is pretty good I must say. The sony A7sii is definitely a low light beast but the Gh5 is pretty good in low light as well. With a fast lens it has too many features to pass up and the image when exposed correctly is a monster as well. Good Luck with your decision! Regardless, you chose two good cameras to pick from so you can't lose either way.
If you get a chance look into the MSI GT72 Dominator Pro. I just bought one from a friend I7 2.8ghz 4th gen 32gb ram GTX980M 8gb graphics 1tb 7200 hardrive with 500gb ssd. Man this machine runs rings around 4k editing with ease. I simply can't believe how fast it runs Adobe Premiere CC and Davinci Resolve! Great Investment I believe the Ghost 60 has simlar specs.