Another book, The Meaning of Crisis (BB, 1984), Ch. Two, "Economic Crisis Theory," esp. pp. 67-99 reviews Marx's theory of FROP and what assumptions are needed to make it work; the relation between FROP and overproduction of capital; and a lot of related matters.
Another book, not by me but by Sid Coontz, Unproductive Labor and Effective Demand, is an underground classic and well-worth a radical economist's time and effort. It presents convincingly a disproportionality theory of the gathering crisis of the 1920s-1933. Too much value producing capacity relative to demand appeared, Coontz argues, not because of overproduction per se but because capital intensive Dept I increased faster then (relatively) labor intensive Dept II. I note that this book is not on Jim Devine's otherwise very helpful bibliography (in his "Causes of the 1929-33 Great Collapse).
As some of you folks know, I'm of the school that rejects "economic" categories when and if they don't do double-duty as sociological categories. That is, theoretical categories must be both quantitative/economic and qualitative/sociological. This is why S/V is the central category in Marxist thought. It is a quantitative measure of the potential (or not) of the system to suffer a realization crisis; it's also a qualitative measure of capital's power over labor. The greater the latter (e.g., since late 1970s in the US), the higher will be S/V hence the greater the problem of realizing value (solved in the 1980s by military spending and hyper-consumerism and in the 1990s by hyper-consumerism (even more than the 1980s) and exports (mainly).
Note the super-contradiction here, that Marx missed. The greater is capital's political power over labor, cet. par., the greater the danger to the capitalist economy, i.e., a contradiction between politics and economics.