I done a lot of experiment with spark and extra weight, basically it will fly up to 130-150g, but
battery life is much shorter and it flies like a brick, not worth it and there is so little weight to strip off the drone its not worth looking for weight loss either.
Best bet is to.
A) Use carbon props so it handles weight better.
B) lighten added payload as much as you can (so look what you can strip off go pro)
C) Buy a stronger drone like Mavic, old ones are cheap now, mavic air while stronger is heavier, so not convinced it will be any different.
D) See if a mavic air motor transplant is possible.
Its not worth it, just buy the mavic air, you'll get better video than anything you'll get out of a go pro and with all the live app stuff and perfect stability.
The spark can handle about 50-60g of added weight, anymore and you're asking for trouble.