Ga4 71 swinger special rarity?

I recently got a 71 swinger special as a parts car. It’s a GA4 car. Basic slant drums auto. Rusty as hell.
I know Winchester is a rare color on any mopar but I have only seen it on 340 a body cars. Never on a base model.
Does anyone have any idea how rare?
Was a running driving car until the transmission gave up last weekend.