The story of the giant nail is a joke, appearing in Krokodil, c1960. I switched back to the tiny nails because it was pretty close to anecdotes I've heard that I'm pretty sure were not jokes. But those were oral, so I can't cite them. Do you accept anecdotes from Alec Nove? I see quoted from p94 of his 1977 Soviet Economic System "It is notorious that Soviet sheet steel has been heavy and thick, for this sort of reason. Sheet glass was too heavy when it was planned in tons, and paper too thick." On p355 of the his 1969 Economic History of the USSR (or p365 of the 1993 edition):

A large number of semi-anecdotal examples can readily be assembled to illustrate the resultant irrationalities. Steel sheet was made too heavy because the plan was in tons, and acceptance of orders from customers for thin sheet threatened plan fulfilment. Road transport vehicles made useless journeys to fulfil plans in ton-kilometres. Khrushchev himself quoted the examples of heavy chandeliers (plans in tons), and over-large sofas made by the furniture industry (the easiest way of fulfilling plans in roubles). [Pravda, 2 July 1959.]