ΔE 12.8, fair: the same colour family, but not a straight swap. Scarlet Blood is a little darker, warmer than Naphthol Pink.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 13). Scarlet Blood is a little darker, warmer than Naphthol Pink.
The same difference applies the other way round: Naphthol Pink is a little lighter, cooler.
ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.
See Naphthol Pink on the colour wheel See Scarlet Blood on the colour wheel
All matches: Naphthol Pink equivalents · Scarlet Blood equivalents