Be in 8th Place with 20 people remaining or 8th place out of 8? I realize more goes into that decision but we are not going to dive into the weeds.

Depends how many chips but give me 8th/8 with 8-10bb over 8th/20 with 20-30bb everytime.

Not sure I agree; if I am 8 of 20 with a workable stack I am pretty comfortable; if I am 8 of 8 with -10 bb I am feeling the pressure. Or to put it another way, if I am 8 of 20 with 25 bb I can let events unfold and pick my spots; if I am 8 of 8 with 8 bb I need to make something happen right now.

While I am willing to be convinced otherwise I would pick 8 out of 20. For this exercise that also supposes that 20 to 2nd pay the same amount and that it is either first or no difference.

Assuming 8th/20 is like 60 BB you probably will have like a 1/16 or ~ 6% of winning. Or more simply, need to win 2 flips to become 1/8, then two more flips to win ~.0625%.

That's because winning 4 flips would mean you have 920 BB, and it makes sense that that would be all the chips given 920/20 players = average stack of 46 BB.

Assuming 8th/8 is like 10 BB. Basically, you will have to win 2 flips so ~25% to become say 3rd/6th, then you have about a 1/6 chance of winning so about a 4% to win. This is assuming the average stack is like 40 BB.
(There would be 320 BB in play so you would need to win 5 flip doubles to bring your stack fro 10 BB to all 320 = .0325%)

If I got exact chip stacks I could calculate it exactly given all players have the equal skill and would just be taking flipping spots with each other for the win.