LOVE Hebrews... i have been so indoctrinated by Protestant understanding od the need for the payment of our sin and Christ paying it for us that i really need some break down and what not :-p
I offer this thought:
There is a debt that needs to be paid. However, the debt demanded by the Law, reconciled by sacrifice, and for atonement of sins, is a debt of righteousness, not a debt of punishment due.
The debt is the Man spoken of in Psalm 1. There was never such a righteous man, never a man who could fill up the Law, until Christ. He's the only one.
We see this in the 2 Philippians hymn:
..."Being found in appearance [literally: schema] as a man, He humbled Himself by becoming obedient to the point of death, even death on a cross. For this reason
also, God highly exalted Him..."
Here it says that God exalted Christ specifically BECAUSE he humbled himself and was obedient even unto death. That is, for his righteousness, not his "propitiation" (a terrible meaningless translation of the original word) or his punishment-fulfilling.
Regarding the Epistle to the Hebrews, the Eastern Orthodox Bible's new translation of Hebrews is fantastic. It's almost completely stripped down and re-built around the Orthodox understanding of sacrifice and atonement, in my opinion. I think it would be just as useful for non-Chalcedonians; as far as I know it does not contain any Chalcedon-specific material anyway.