It's rare, the EL5 is a high impact special order paint, it isn't a super rare color in 71 but the white top and stripes combined with the EL5 make it rare. One main reason is the J54 sport hood option on the demon 340 was ALLWAYS painted with the blackout so it would be an extreamly rare sight to see any demon with a sport hood blackout and a white strip / top with the posible exception of a black demon !! Your car looks like it was a flat hood correct ?
Here is a pic back in the day of what looks to be a black demon 340 with sport hood, black top, and white strip!