I do think that to speak of the quantitative identity of profit
and surplus value is an irrational formulation.
One could express what marx was getting at in what would be
a formally correct way by talking about a quantitaive identity
between what profits ( in money terms ) would be if all prices
were proportional to values and what they would be again
in money terms if we add the constraint of an equal rate of
profit.
I also am in full agreement that one can measure relative
values as exchange values, but not absolute values.
One measures relative weights with kilogram weights, one
expresses absolute masses in terms of hadron number.