Trying to figure this all out (aftermarket stereo system)

Hey all.
My recently bought '69 Cuda has a big 'ol stereo system in it that could be nice if I could figure it out.
The PO put a Pioneer head unit in the dash with a 20 disk CD changer in the trunk. A pair of 16" subs, a couple of 6x9's in the back and a couple of 6" rounds in the doors. Backed this all up with what I am guessing is amps and what-not.
The wiring is an "ok" job.
But none of the amps and such are bolted down. I have no clue what needs securing, better wiring, or tossed out and replaced.
Add to that all the stereo shops in my area are closed for the time being.
Attached is pictures.
Any suggestions would be greatly appreciated. 20200427_115407.jpg 20200427_115443.jpg 20200427_115400.jpg