Just doing the math, you're looking at needing 4500kbps average for your video bitrate to hit 2gb/hour. For 720p60, depending on what you're actually recording, that's not going to result in good "recording-level" quality -- that bitrate is more or less in the butter zone for twitch streaming though, where it's expected to have a lower quality just due to bitrate constraints, as well as tailor to a bit rate that's friendly for lesser bandwidth-capable viewers.
Normally the recommendation for recording is to use a quality-based encoding method, such as CQP or CRF, but if you're seriously limited in space, then this is one situation where I would recommend trying out variable bitrate, with the target range around that 4500kbps mark. Just temper your expectations as far as just how good a quality you're going to get -- it won't be much better than what you already have, but heavy action segments should have the benefit of being able to use more bitrate as necessary, with lower action scenes making up for it in the long run.
If the tight margin isn't really *that* necessary, then what I would really recommend is determining which CQP/CRF quality level gets you around where you want for the filesize/quality tradeoff, and stick with that. It will result in a much more stable overall quality, albeit with a bit of a more volatile overall file size... but for recording purposes, that's usually what's desired. Unfortunately, you're probably going to be looking at a quality value of 30 or more, which again... don't expect miracles. It's just a way of evening out the overall quality across the entirety of your recording.
