These may help: https://www.thephoblographer.com/2016/09/27/what-to-expect-from-the-fujifilm-gf-lenses-with-their-full-frame-equivalent/#:~:text=What you get when you do this is,f%2F2.2 GF 63mm f%2F2.8 %2F%2F FF 50mm f%2F2.2
https://shuttermuse.com/fujifilm-gfx-crop-factor-and-gf-lens-35mm-full-frame-equivalent-focal-lengths/#:~:text=Most people are used to seeing lens focal,to a 50mm lens on the GFX system.
I believe the 0.79 factor is for going from GFX format to FF format, I am not certain whether you use 0.79 or 1.6 for adapting FF to GFX.
But try not to get too hung up on that. After a while, it will be just like using any other format; put a lens on the body, turn the camera on and look through the viewfinder, if you need a different field of view, change to a different lens😁.
edit: p.s. Please let us know what kind of results you get, I am curious whether or not you get a “bright” center image circle vignetting out to a black rectangle.
