Walther PPQ Polymer and Steel Frame parts interchange

[sin3rgy]

I've got a the polymer but getting the itch to get the steel frame. Just wondering if the parts like barrel/slide/recoil springs etc can be interchanged? If so I'd probably keep the polymer, if not I'd probably sell it. I know the frame of the SF has some changes and some parts can't be switched, but what about the slide components?