My 2 cents...
Don't worry about the dash. Instead, start changing the big outright-wrong stuff back to factory. Battery, GM distributor, etc
At this point with non-original engine, getting things perfect (ie a $1500 dash with only minor differences) isn't worth the cost, but the big stuff that anyone with even a passing knowledge of Mopars could look at and say "that's not right!" would prob be worth fixing.
Really... 71 gills, billboards, go wing, louvers, shaker... really iconic E-Body / 'Cuda stuff... if you're looking for things to increase value to the average prospective buyer, that would prob be it.