Hi sussamb, I realise now the Loft Beck route is the low level C2C route and you would know about it already
Looking on an older paper map I can see a trace of a path starting at the grid ref you mention but on a newer version of the map it is showing as a fence. From Haystacks summit we have walked near and alongside that fence when we have explored Haystacks summit area and there is a trod of a path. I don't know if this path starts alongside it from near Scarth Gap mind. At least I've not noticed one. There are a few paths and trods to explore across the summit away from the main path; we have been to see Wainwrights perched boulder a few times and been on some of the other little tops. In Wainwrights The Western Fells (second edition revised by Chris Jesty) he does indicate a route that goes through scree and avoids the scrambly bit but he recommends using the usual route from Scarth Gap. I do remember reading somewhere years ago there is (or was) a path avoiding the scrambly bit but I haven't looked for it because I'm not fond of scree.
I see you are starting in early March so we may have recce to see if we can find that path, I feel like having a bit of an explore up there
Squeaky hasn't done Haystacks yet so we may go up there if there is some nice weather in the next few weeks.