Architects Purcell UK and designers Casson Mann have been unveiled as the creative team to take the bid forward.
Craig Riley, from Casson Mann, said they aimed to build on the city's history of "standing up to injustice".
The Heritage Lottery Fund has earmarked £12.9m but is waiting for final proposals before releasing the money.
During the medieval period, Nottingham Castle was one of the most powerful in England but it was systematically demolished after the Civil War.
After years of debate about what to do with the site and failed funding bids, last year an initial £600,000 was approved by the Heritage Lottery Fund to allow detailed plans to be drawn up.
Earlier plans focused on Robin Hood but the current scheme incorporates the city's wider history of political activism.
This includes a gallery exploring rebellion in the city and plans to open up more of the caves with a glass lift.
However Mr Riley said stories like the famous outlaw's archery contest at the castle would not be forgotten: "While this is a legend, it represents this spirit which has been observed in Nottingham people of standing up to injustice.
"On the one side being rebellious but always having a sense of what is right and making sure something is done about it."
The full bid is expected to be submitted later this year.
A firm appointed to design Nottingham Castle's new £24m visitor attraction has said it wants to capture the "spirit of the city".