Ugh. Sudden flashbacks to having to switch analog output between Japanese NTSC (no pedestal) and US NTSC (with pedestal) without getting weird noise in the black regions.
But IIRC the MPEG-2 standard had luma==235 -> 100IRE for all of the analog formats (pal/ntsc-j/ntsc/secam) so I'm not sure why you say that would violate the broadcast limits?
Simply because the math works that 7.5IRE on a 120IRE scale maps to 16 8-bit that 110IRE maps itself to 235 8-bit on a simple scaling equation. To get 235 8-bit to match to 100IRE means some sort of exponential scaling. At that point, I stuck with the linear scale and moved on with the keep it simple stupid mindset
But IIRC the MPEG-2 standard had luma==235 -> 100IRE for all of the analog formats (pal/ntsc-j/ntsc/secam) so I'm not sure why you say that would violate the broadcast limits?