Who would win, Indy car vs F1 on a Indy track / Indy vs F1 on a F1 track (like Monaco)?

The F1 car would easily beat the Indy car on an F1 track. But on an Indy track the F1 car might not be able to match the top speed of the Indy car unless it had a lot of downforce taken off of it and that would make it unstable.