Parts kits have been around the shows I went to for years. Walthers were a little rare but about 20 years ago I did pick up a pre war commercial PPK kit that had a set of 95-98% grips (screw runs L to R), a high gloss 95% stripped slide and other assorted parts for $40 if my memory serves me.
The grips I got are pretty nice. I am not an expert by any means, but they are up there in condition. I have a picture of my PPK with the grips on, but I took them off immediately and put on some made in India grips. I didn't even put the screw in so I would not do something dumb and over tighten it.
Whether those .32 parts will fit depends a lot on the specific PPK .380 you wish to put them on.
The recoil spring and ejector are definitely not interchangeable. The internal decocking lever is unlikely to work correctly. The grip, hammer block and trigger bar might or might not fit a postwar gun. The hammer spring seat is redundant on a U.S. made PPK.
Thank you for the input. I will try to find a .380 slide, see if it fits and see how she functions. Hope for the best. I was about to send my HI-POWER to Cylinder and Slide, but looks like this frame has priority now.