Thanks, I'm sure that's a very nice fork and a generous offer, but this is just a mechanical project/experiment. And I have tried mixing forks for different size frames before and had bad luck, something just doesn't feel right in the handling. That one looks kind of like it has less offset than likely suitable for this small frame.
I actually did put the parts of this project together dry just out of curiousity, and it felt doable. I hose clamped a shim onto the stem above the top nut of the headset to give this extension portion backing as the headset is tightened. tightened the stem into the fork first (fully inserted, actually bottomed out into the intact fork), then tightened the headset. Felt pretty good and could probably do a short smooth test ride like that without glue, just the shim and hose clamp above. Definitely not something I would trust for anything more than a level test run, but it was pretty easy to set up and could allow me to at least get a feel for this fork, sometimes you don't need much to get an idea about a fork's suitability.