Rear Axle 5 lug conversion questions

[blkcorvair]

I have a few questions that I am having trouble siftying through threads to answer.

I have 2 rear ends right now.

1) is a 55" Posi 373 from my 69

2) is a 57" Open 3:08 from a 1970

Can I remove the posi and gears from my 69 rear and install them in the longer 1970 case? Than would I be able to find a set of used 5 lug axles to fit? Can I use 5 lug axles from 71-87? What year brake drums should I be after? The original 69 Backing plates and shoes can be retained correct?

Thanks guys. In the end I am trying to end up with a 57" long rear with a 373 posi and 5 lug shafts and drums for as cheap as I can.