Speaking finish types only, Cerakote is great for 1911's as it doesn't add a lot dimension--it's very thin. Parking is going to be a little thicker, so consider that if you have tight tolerances.
Speaking on value, I would recommend you keep the original finish and leave the gun stock. It may be "nothing special" today, but that can change in the years to come. Admittedly I'm no expert on 1911's, nor specifically Springfield 1911's, but I do know that over time the desirability of a particular date range, or serial range, can sometime go higher than one might ever imagine. A Cerakote job, or even a re-do of the same original finish type will destroy a gun's value if it would have been considered collectible in original condition--worn or not.
But really beyond that financial value, I personally would find sentimental value in keeping it like your old man had it. How cool would it be to find a photo of him holding that same gun, and you have it preserved in the condition he left it? If it really is "nothing special" in terms of financial value, what's the harm in buying an inexpensive 1911 like a Tisas (surprisingly good quality for the money) and building it up as you would like to with the Springfield? That way, you can enjoy the 1911 setup that you "want" while keeping the old man's 1911 in it's original condition.
Your gun, this is just my opinion, but I'd keep it original. If you do cut into it, and refinish, Cerakote is a great product for 1911's due to it's properties.