Yes, definitely - on top of a shared of the conversion cost you obviously have all the track installation and infrastructure costs as well, so wouldn't be cheap. Against that then you obviously also have a much larger capacity to offset the costs, and I do think a London SGP would sell well.
This is what is on this summer, and, as athletics is included, the oval configuration will be in place
https://www.london-stadium.com/residents-information/index.html