An immortal body of flesh and bone must then be animated and maintained by something besides circulating blood and that is what distinguishes it from a body of flesh and blood.

Must it? I mean in Eternity, all bets are off when it comes to our understanding of the physical universe (not that we can even completely understand the one in which we currently reside).

I think we're getting into the area where Faith trumps Sight.

1 Corinthians talks about the bodily resurrection. That includes all bodies, not just the ones buried nice and neatly in an airtight coffin. It includes "fish-food" (burials at sea), "worm-food" (decomposed and eaten bodies), and the incinerated (whether by cremation or at the stake by the "well meaning" papists).

Just try wrapping your head around that one.

As for whether is was the Blood or the Breath of Life that was the key component of our immortality, it may have been neither.

Adam and Eve were ejected from the Garden before they could eat from the Tree of Life. Judging from Genesis 3:22, it sounds like it was necessary to do so before they could eat from the Tree of Life and live forever in their sinful state. Everlasting life in this circumstance required neither blood or breath of life.