If i can remove front part... please look at second photo, it is removed and the body is 'cleaned' from misc parts.
I have bought a cheap junk non functional camera just to start this project. Front part is fully functional, i mean mechanical.

Thank you for support, this is what i need.
Yes, i can mount the body with rail in tripod. I will take another photo.

yes, exactly, this is my plan. I want to cut the alloy body so i can put SQ body on it and center of the bayonet of the sq will be centered to front frame of the gx. Maybe i will integrate my quick release plate.
Great idea about darkbag cloth, thank you. Len me check some info about ho can i make small bellow. If you have some, please share.
And yes, main concern is lens... i think it should be 127mm at least. Is it like a distance from the lens to the film, isnt it?

Not quite a problem, it is an electronic triggered seiko shutter, just to find out the right contacts. And i think GX lenses has image circle wide enought to have tilt/shift for 6x8 area (my SQ is 6x6 'only')