I think it would hold up pretty well under m90-m120 weight springs as long as the spring guide is well supported by the buffer tube screw. I tried out similar on a shitty ka gearbox that’s cracked that’s most likely going to go into a reaper hpa build.
It would work better with a shell with no tab cutouts, so you could slot the top wide enough to slip the spring & guide out, but retain the sides to support tail of the gb shell for the spring guide