Gutted a basement and found a window, what should I do?
Unless the existing window is leaking, the sole criterion for judging better and worse options in this case is the likelihood of future bulk water infiltration.

The current installation is performing functionally and aesthetically as part of the building envelope. Breaching and patching the envelope is not a repair, and at best will only perform equally well with the current situation in regard to the prevention of bulk water infiltration.

From an insulation standpoint, the cost benefit analysis should factor thermal performance based on the weight of an empirically proven installation versus untested new construction and the requirement that the new construction must occur under less than ideal conditions (i.e. under a porch).

The existing window wasn't a problem a year ago. It isn't a problem now. It is unlikely to be a problem a year from now.