Is there some market data subscription I need to be able to chart bond prices more than 6 months back?
https://fred.stlouisfed.org/categories/22 wouldn't the price of a bond converge to par over its maturity?
Spread and Duration. You don't need/want Options charts, either. The exposure is constantly evolving.
That would work as you look at different terms with a fixed duration. Not a chart of the bond value, though. I am not even sure I should be looking at ZN Futures. There are a lot of adjustments to make to visualize it against other assets.