2704x1520 zoom capabilities on a 1080 timeline

I have a mixture of 1080 footage and some 2.7K footage which I shot on the GoPro.

I am editing my footage for a 1080 timeline and will be exported for this so I was wondering what is the maximum zoom I could do on the 2.7K footage without dropping the quality of the image?

I know if I set the clip to be 150% zoom that would mean my original footage would need to be 2880 x 1620 for no image quality loss, so I have been putting the footage in at about 135% at a guess when I want to zoom in a bit, but it would be good to know the exact number I can go too.

Select a GoPro clip in your Timeline.
Go to the Inspect to the very bottom.
Change "Spatial Conform" to None.
Now your clip is at its native size, and you can probably enlarge it another 20-30 percent, maybe more. It depends on the clarity of the original clip. I shoot 4K and edit in 1080 Timelines daily. Different cameras and different camera operators give me stuff that can enlarge more, some less, before looking like garbage. Really depends on the clip. But changing Spatial Conform to none gives me more zoom than I usually need anyway. Except with drone shots, which I can enlarge more when there's less movement (less motion blur).

Experiment, try it out. Know that you can make that one clip a Range, export, it'll only export the selected range. which makes testing really quick.