I wouldn’t use DNxHD 36, this is meant as a proxy format and while you will be saving space, you’ll also be losing quality.
Apple Intermediate is an 8 bit 4:2:0 codec meant to use when you’re editing long-GOP formats such as HDV. While mpeg2 is long-GOP it sounds like you’re shooting 50Mbps 4:2:2 video, so by using apple intermediate you’d be losing that color fidelity. Rather than spending the time to transcode all your footage and end up losing either bits or color fidelity, I would just store my footage as native mpeg2 mxf. It’ll save you time and quality to just archive it native.