Dear Andrew :
The passage you quoted might be a textual evidence of the claim that
Marx was against simultaneous determination of the PRICES of inputs
and outputs. But, I think, it can be COMPATIBLE WITH VALUE AS A
SYNCHRONIZED CONCEPT.
Korean translator of 'Capital' added translator's note as follows, and I
entirely agree to his interpretation.
"...It can represent a deduction from value. [INCREASE IN THE
SURPLUS PRODUCT DOES NOT ALWAYS MEAN AN INCREASE
IN THE SURPLUS VALUE. BECAUSE THE VALUE OF PRODUCT
VARIES]. Otherwise..."
As values of input and output are evaluated at the same point of time,
the falling of the value of yarn will not automatically show an increase
of the rate of surplus value. Namely, the value of cotton will decrease,
too.
Happy new year!
Rieu.