Bummer about your Dad, but one silver lining is he did not disappear in a moment with zero notice! Take advantage of the time you have left with him to whatever extent possible!!
I echo the sentiment of most here, but I would put a bit of a twist on it ;~)) I would say, find a PS instrument at one of the dealers that you really like that is available today. From your description of experience, I doubt that you are set on having a specific wood for the neck, another specific wood for the body, another specific wood for the fret board, bridge pickup X and neck pickup Y, etc. There are a LOT of beautiful PS's floating around looking for a home that would definitely lift your boat (more on that in a minute)!!! The big advantage to this path as I see it is, you will be able to take possession of said six stringer, and actually play it for your Dad! He will be able to hear and see you enjoy this gem of an instrument, and I think with that added to the mix, it is worth more than designing one that he may never see or hear.
As for "Am I worthy", I went through this same mental exercise last year. Now, I am decades older than you, but I wanted a PRS for over 25 years, but always shied away from the money it would cost for even a core model, and I did not want to settle for an SE (I've got a bit of a "must be made in America" complex for some items). In December of 2020, I was starting to make a lot more music and decided, I am getting one. Took me about 4 weeks of searching, but I found a Wood Library McCarty 594 Hollowbody II that I instantly fell in love with. Three hours after seeing it I had paid for it ;~)) About two weeks later it was in my hand and I fell in love with everything about it! I did not feel I was worthy, and did not need a guitar of this caliber in some senses. But then I also know that it made me so happy, and that any discussion of "worthy" was a waste of time for me to wait for the point in which I felt that good about myself before I bought a really nice piece of equipment. I may never get one with that kind of logic! And most of the time, this "are you worthy" question is one which is imposed on us by society and it's manipulative hidden messages about self worth. I could not be happier with the decision to get the guitar I was not worthy of ;~)) Which takes us to the other two that I bought after I got that one! I did NOT NEED another guitar (or two), and the one I had just acquired was fulfilling all I could want in playability, tone and looks wise for the time being! But I had a special event in my life that I did not realize was going to happen, and I decided to track down PRS guitars that shared the date that matched that emotionally significant moment in my life! I found 4 all together, I was able to purchase two of them. One I did not really care for and the other one got purchased by someone else before I could pull the trigger. Both acquired were CU24's, they were both "born" on the same day (twins) and I will cling to them both until the day I die! One is a Core model and the other is a Private Stock! Now again, I did not feel "worthy" but the same arguments above convinced me that I should not wait because trying to find guitars in the future that matched up with that special date would be a real PITA. I dug myself into debt to get these guitars even though I did not NEED them, did not feel I was worthy of them, but wanted them enough to do what I had to do to get them. I am psyched that I did. That PS feels even better than my Wood Library HBII and the Core CU24 has a bite to it that scares me at times! Maybe it is the PS frets, maybe it is the Hormigo fret board wood, whatever the case is, it is mine now and I LOVE playing it as well as the core model! Now neither are getting as much time as my HBII in large part due to the type of music I was doing in most of 2021, but that is going to change soon! And when it does, they are coming out to PLAY! I take exceptional care of all of them, and am not going to be "passing them around" for everyone to play, but they will get played and not live in their cases (well, they will when not in my hands)!
Long and short is, make your Dad happy by letting him make you happy! And never feel that anything is beyond what you should have, it is a societal restriction that keeps people from achieving what they really want in life!! These guitars allow me to play stuff I could never play on my strat or other guitars (this is the lift your boat part) and therefore make me be able to play better, and have prompted me to play longer, so that alone is worth the price of admission!!!
Blessings to you, your Dad and his health, and I hope you are able to joyously celebrate the time he has left! Hopefully to the sound of you playing that gift he wants to give to you!!
P.S. Read "The Fountainhead" by Ayn Rand and you will loose any inhibitions about your self worth! I first read it when I was your age almost exactly and have read it half a dozen times since then!! It changed my life!!!