Some D frames of this era did have info written in white on end flap of woodgrain box. Most I've seen were DS's in .32 NP caliber since Colt did not make a specific gold foil label for these. Where was the info printed and what color was the writing.
I agree that the info written on the label looks OK. I don't know anything about white paper labels on these; my 1970s DA Colt boxes all have gold foil labels but I don't have a Cobra from that period. I also agree the $1200 is high for that gun.