My guess is the Tories will pick a RW Leader.
Their bind is this. If they pick a LW Leader some of their supporters will move to Reform. If they pick a RW one, some supporters will move to Lib-Dems or Labour. If they start cuddling up to Reform, a lot of supporters will walk away.
Strangely, much depends on how Labour do in government. If they pull the right levers, they will shoot a lot of Reform's foxes. BTW, I am almost certain immigration numbers will fall, even if Labour do nowt. And they won't do nowt.
A Tory-Reform amalgam will appeal to maybe 20% of the voters. Maybe 25% at a push. Not enough.
The snag from a Tory POV is that a more moderate position might take a long time to bear fruit unless Labour fuck up badly and a whole host of centrist voters start looking for an alternative. But as the Tories have absolutely poisoned their brand, those people could as well go Lib-Dem as Tory.