PERHAPS YOU CAN FIND AN 80 YEAR OLD MAN OR HORSE WITH LONG HAIR THEY WILL PART WITH. THEN YOU COULD TRULY SAY IT WAS A OLD REPLACEMENT. RESTORED OR AS FOUND IS ALWAYS A HARD DECISION BUT A GOOD RESTORATION DOES MAKE THEM LOOK GOOD.
I certainly prefer the good restauration. Long as you can make all retrograde and you declare the piece in question as restored it's not a mistake IMVHO.