YES, it was an available interior OPTION, but
it looks like "triple green" was the norm for 1970 - out of 56 green R/T fender tags, I have just ONE example with white interior & it is possibly the most desirable combination today (for a green car) boogie tell us more

Quote
I have fender tag info on 19 "FF4" Challenger R/Ts with the following interiors/roofs:

1 with HRX9 - black leather/vinyl
2 with H6X9 - black vinyl
5 with H5F8 - green cloth/vinyl
11 with H6F8 - green vinyl

1 with white vinyl top
3 with black vinyl top
4 with painted roof (FF4)
10 with green vinyl top
&
1 with "unknown" top

and I have fender tag info on 37 "EF8" Challenger R/Ts with the following interiors/roofs:

1 with H6XW - white vinyl apimp
2 with H6T5 - tan vinyl
3 with HRX9 - black leather/vinyl
5 with H5F8 - green cloth/vinyl
6 with H6X9 - black vinyl
20 with H6F8 - green vinyl

1 with gator vinyl top
7 with black vinyl top
8 with white vinyl top
9 with green vinyl top
10 with painted roof (EF8)
&
2 with "unknown" top


there is a lengthy GREEN Challenger thread on e-bodies.org scope

1970 green FF4/EF8 Challenger R/Ts and green V1F vinyl tops