All depends on who you would sell it to.
If you were to try and sell it to someone more your age and more into the hot rodding of the cars they would take it with a slightly increased value than projected from KBB.
Someone like your dad (and even mine unfortunately) believs in leaving everything 100% stock which I can't totally blame, causes less complications later on and is one less thing to have to deal with replacing down the road (like special ordering from the net).
My dad has a 87 Fiero GT with 5 speed. I have tried to talk him into putting in a 3.8 SC or just even a 3.8, even a 3100 to compromise for the old 2.8, but like he always tells me "it makes it more special to leave it all stock." My response, "its even more special when hot rodded!" Oh well his car he can do what he wants I suppose!