I also would like to do these toe-up as that’s how I prefer socks, also to get them as long as the wool can make them, but after looking at the pattern I think these will just have to be toe-down. The charts could be reversed if you wanted to - I’d print out multiple copies for every repeat, and tape them together in the same way they’ll be knitted, and then knit from the top rather than bottom - but if you want to keep the nice detailing on the heel, that might be tricky. It is possible to do flap heels bottom-up, but not common except where people have tried to do it for the sake of it, and I think the conversion would be quite difficult, especially with the slip-stitches lining up. Occasionally I find a sock pattern is exceedingly difficult to reverse and I’m better off doing it as written.
If you are happy with SR heels, it would be doable, I think.
There are various reasons to prefer toe-up, and ways to get around most of those. What specifically is the reason you want toe-up for these?
Does anyone know for sure whether you can do a slipped-stitch SR heel?
Laura, if you do try to convert to a heel-flap toe-up, knitty’s Widdershins may be a good start.