Before the industrial revolution, the pastoral society that Marx seemed to defend was possible,

Karl Marx did not defend a "pastoral society". He and Engels had a giddy enthusiasm for the industrial revolution and for science, and saw continuing industrialization as what would set the stage for the development of Socialism.

but no barter system could possibly work in a modern industrial society.

Karl Marx did not defend a barter system, and in reality no such thing as a society based in a "barter system" has ever existed (see: David Graeber, Debt: The First 5000 Years). Barter when it exists is usually in erratic spot trade among strangers or between people who live in a monetary economy and then are suddenly put in a controlled framework (like a POW camp), but as a systemic social relationship it never existed.

Imagine the thousands of parts that go into the manufacture of an automobile, how would you ascertain the correct barter for each one? Imagine the millions of different products available, how do you determine how many of each must be produced?

Yes, the economic calculation problem. It is an important and highly theoretical question and different types of Socialists have given many different replies, though Marx himself never wrote much about it. Marxist-Humanists usually argue that, when relations of production become immediately social, labour-time accounting combined with a democratically-determined measure of utility is enough to rationally come up with a standard of value for economic calculation (i for one think their standard of what constituted "immediately social" labour is too vague for this reply to be a strong one). Marxists like Cockshott and Cottrell have written a lot on the possibility of using computers and labor-time accounting to develop a rational system of central planning, though i also think their reply is very weak and don't agree with it.

Robin Cox has argued that so long as the Socialist economy was very decentralized and spontaneously ordered via a self-regulating system of stock control, then decision makers would be capable of allocating resources rationally using calculation-in-kind (this is similar to the Anarchist reply to the problem and is incompatible with Marxist centralism). My own view is that a mix of decentralized and spontaneous stock control combined with labour-time accounting could provide a rational mean for calculation-in-kind to be done, even if this goes against the Marxist conception of a "common plan" which i disagree with in the first place. But all in all i don't see how this is relevant to the discussion of Marx's critique of Capitalism, and this subject has gotten outside the scope of this thread (to discuss and explain the original thought of Karl Marx and Friedrich Engels) so i will continue this in PM if you wish.

That's the role of the market and that's why people would find plenty of rubber boots but no dish washing soap, or vice-versa, in Soviet supermarkets. Central planning cannot make good predictions because they don't have access to all the information they need.

Oh, i agree.

I think Marx totally missed the big transition society was going through. He was ranting against feudal society, at a time when feudalism had already become irrelevant.

This is a common misconception but still a misconception, and a read at Das Kapital shows why. Marx spends the entire 3 Volumes giving a detailed outlook on the inner logic of the production and circulation commodities, systemic wage-labour, the origin of profits, the accumulation of capital, the equalisation of the rate of profit, the centralisation and globalisation of capital and the continuing technological development under capitalist production; i.e all features of the industrial capitalist society. His discussion of primitive accumulation is merely a discussion of the historical process that set the stage for all of this to begin, not the whole picture. Marx was a theorist of Capitalism through and through.

Marx's view of Capitalism is that it is a system with many different "tendencies" towards instability and "counter-tendencies" towards stability. The relative strenghts of these tendencies are related to a wide diversity geographical, technological and economic factors, and the interplay between these tendencies is what sets how well Capitalism is doing. His view however is that the factors that rule the counter-tendencies tend to be historically limited (that is, they can be exhausted) while the tendencies have the potential to grow indefinitely (as the economy industrializes more and more, the rate of profit tends to rise and fall cyclically - but getting on average lower over decades - and this sets the stage for economic crisis that are an unavoidable aspect of Capitalist production), hence Capitalism like all other modes of production that preceded it is historically limited and will inevitably be ruptured once the development of the forces of production outpace it's limits.