I've done 2 of these, one on my 2dht in 66, and lately on CUDAVRT, Two holes needs to be punched in the radiator support so the pigtails from the 'Cuda turn signals will have sufficient clearance. Also I made an L bracket to help support the outboard sections of the grille, at the top.
Biggest problem was crafting a hood release. However the later '65 Plymouth Valiant hood had a latch release built into the "Plymouth" emblem on the hood front. Didn't know this before, and it is a bolt in, much easier than rigging up a cable release.
Stroker