Taking your three improvement players Austin, Mirallas and " a top CM" , how much do you think that would cost? Not much change out of 60m, I'll wager. And not much improve the either imo.
Mirallas is supposedly Lennon + 3m
Austin is around the 10m mark
Those two would provide superior cover to what we have had this season - both could in theory push for a starting place if they replicated their best form.
CM wise I don't know, McCarthy is valued at 20m so would use that as an idea of what we're looking to spend - so all together the same amount (give or take) as you're willing to spend on a forward because you have doubts Kane will be as good as last season, 3 positions improved (starting CM, and RWF/CF back up) vs one position we don't even need improving (starting CF) ...