Had an axle flip?

[K10mashup350]

So I recently bought a "86 c/k" that has 2" drop spindles (possibly cut/lowering springs as well, sits really low) in front but the back still up at stock height (looked like a drag car really gay looking) so I brought it home an figured I would do a flip kit with c notch to "level" it out an as I got looking into the flip kit an looking at the rear suspension of the truck more I noticed that it had been done once already, the notch is in the frame already and they moved the upper shock mount down n closer to the rear as well as drilled the offset holes in the ubolt plates, so as it sits an as far as I can tell all I need is a new spring perch (don't know how they had it before but can see where it used to sit)

So my questions are do I need anything other than the spring perch?

Is it safe to move the upper shock mount as opposed to the ones that come with the kits for on the axle? Or stock location with lowering shocks?

An once this is done is there any "easy" way to reset the pinion angle an shaft to correct location from being "pushed" forward with the flip?

Thanks in advance guys I did search these things but I didn't come up with anything 100% on what I was looking for maybe it was my keywords?