Backtape off the lower contour, blend up but not to it, polish back the blend. Color match will be critical and probably not easy. Pigments & chemicals are different now, but toners & metallic can be adjusted to get it right. It'll be time-consuming, and production-shop painters won't be interested, but there's the occasional painter who can appreciate the task and the challenge. A BC/CC can be applied to match the OEM texture, but they generally have more depth to the finish; might not be an issue on a lower quarter if you can't for some reason use a single-stage.