I do not have a RH valve cover that matches yours

here is the '71 big lip RH valve cover

yours appears to be the same one I should have on my mid-July '70 built Challenger R/T (LATE '70 & EARLY '71)

did yours have studs or bolts on the outside corners & what's the SPD & plant of your RR - do you also have the Engine Assembly Date (EAD) off the pad by the distributor?

moparts 1971 late BB valve cover RH.JPG