A904 front planetary and washer question

IDK on all counts, here
I think up to and including 66, all older aluminum case guts interchange.

TrailBeast has the scoop on installing the A500

Check out the gear stuck in your sunshell. It should be the same size on both sides. This indicates the standard 904 ratios.

If it has a one-piece sun-gear, with two different sized gears cut onto it, , that would indicate the wide ratio A999 gearset.
Your planetaries have to match that sungear, and as you probably have seen, the front and rear are different.
The A500 will let you run any pumpkin you want; and the bigger the better.... they say. But honestly if you can hit 60mph at the top of second, that is about all you need; so 4.30/4.56s will get you close,lol.

Hooking it to the pushbutton? Hmmm,you're on you own there.