OK, so it's a gift and has sentimental value. And you don't want to get rid of it. I totally get that.
But you want to totally gut it and replace the neck with something not original and make it playable although a mongrel, and you don't even like Fender type guitars to begin with. Do you really think you're going to enjoy playing it? You think you're going to even play it at all? And as for sentimental value...well, you've ended up just about destroying that anyway.
I'd say that you need to enjoy that guitar, relish it, even if you never play it. Put it in a display case and hang it on your wall so you can see it everyday and appreciate its sentiment without changing it a bit. Then get yourself a guitar that you will love to play, that inspires you, that you get satisfaction and fulfillment from playing.
What type of guitar is it that rocks your boat? LP? SG? Jackson? "V"? Firebird?
Man, there are hundreds of great looking, great playing, great sounding, and inspiring guitars on the market for less than $500!!!
Believe me, you'll be way happier in the long run if you keep your sentimental guitar untouched and buy yourself a guitar that you can be happy just playing.