Another basement insulation question

Hello and thanks for the help.

I'm getting ready to start the finishing work on my basement renovation. I'm probably going with 3/4 rigid, then studs, then Roxul unless someone tells me different.

As part of the renovation, I did a basement excavation and foundation underpinning. This gave me 9 foot ceilings in the basement, but it also gave me a foot wall about 3 feet high and 3" in from the original foundation wall.

So the question is on the rigid insulation. Should I just go straight up from the bottom and leave that 3" gap open behind the rigid, or should I cut/tape/foam the rigid flush against the bottom and top walls?

Thanks!