Looks promising but you'll have to cut the original model into segments. Far as I'm aware the PPK uses three models, one for the Body, one for the Slide and one for the Grips. You'd have to cut the pistol into parts and replace them individually and then edit the main model file to make sure it fits back together properly and isn't clipfest 2015. Then cut up the textures and probably redo the UV mapping on each piece individually to fit the cut up texture. Not sure how TF2 handles the models but SFM models tend to have a lot more individual textures than PD2 has. Had a few cased where I fused 3 or so textures into one file with a reworked UV map just to get it working without using bundle patching.

If you keep the aspect ratio of the image the same size, there is absolutely no reason to mess with the UV map.
You can also edit the material configs, so you don't need several copies of the same texture file.