GLA chair of the budget and performance committee John Biggs warned of a "doom-laden scenario" on the budget for the next three years.
"Everybody talks of the risks of this becoming a white elephant in terms of worst outcomes that would leave a hole in your budget. Have you strategised the covering of your costs?"
London Legacy Development Corporation chief executive Dennis Hone said: "We've looked at a range of outcomes and scenarios but it's a work in progress. We are finalising our budget submission in the next four to six weeks.
"But we are content with the position at the moment. We have factored in our needs going forward on what we would need to maintain things like buildings if they don't pass into the hands of others."
Much depended on the state of the property market, timing of land and property sales and the structure of the sales. His team was looking at several finance modelling systems.
Hone said the park has been allocated £300m of public funds for capital spending and £200m for transformation. The London mayor Boris Johnson had committed £10m a year. The park will generate an estimated £1.1bn pre-tax in sales of land.
Biggs also asked the corporation if it was trying to emulate the "spectacular" success of New York's High Line elevated freight-rail-line-turned park, which involved the same landscape architects as those used in the 2012 Olympics.
Hone said: "we are using James Corner Field Operations on the South Plaza - a series of outdoor rooms and little amphitheatres and children's play areas.
"It will be a fantastic garden with several aims and we want people to come all year round. But it is one element of the offer and we have to look at the collective offer."