>>4415100Those should work just fine, I would go with the a7r, because it has a pixel shift feature, which aside from the resolution bump is mostly important for increasing the color information at each pixel to help minimize the effect of the bayer filter.
I found tripods want to fall over due to the weight of the camera, or if I shortened up the legs to prevent it from falling over, I wouldn't have the working distance for the macro lens so personally I bought one of those purpose built stands for the scanning camera and I use a cheap bubble level to make sure it's pretty close to parallel with the film to avoid distortion.