Another interesting late Marx letter is the drafts and reply to Vera Zasulich: https://www.marxists.org/archive/marx/works/1881/zasulich/
One of the really neat things about the drafts it that Marx's deletions (in the manuscript, crossed out) are indicated with square brackets. Really gives a sense of Marx's thought in process. Also lots of indications of him rephrasing to be less rude.
Note: Marxists.org has placed quotation marks around first and second. This is because the 'second' draft was actually written first (Riazanov mislabelled it in MEGA1 😔 )
The draft labelled 'second' on Marxists.org actually begins discussing the very topic of the (lack of) suprahistorical validity:
I. I have shown in Capital that the [transformation] metamorphosis of feudal production into capitalist production had its starting-point in the expropriation of the producers; and, in particular, that ‘the expropriation of the agricultural producer, of the peasant, from the soil is the basis of the whole process’ (p. 315 of the French edition). I continue: ‘Only in England has it (the expropriation of the agricultural producer) been accomplished in a radical manner. ... All the other countries of Western Europe are following the same course’ (loc. cit.).
Thus [in writing these lines] I expressly restricted [the development in question] this ‘historical inevitability’ to ‘the. countries of Western Europe’. So that there should not be the slightest doubt about my thinking, I say on p. 341: ‘Private property, as the antithesis to social, collective property, exists only where ... the external conditions of labour belong to private individuals. But according to whether these private individuals are workers or nonworkers, private property has a different character.’
Thus the process I [described] analysed, substituted a form of private, fragmented property of the workers- capitalist property(a) of a tiny minority (loc. cit., p. 342), substituted one kind of property for another. How [ would it apply] could it apply to Russia, where the land is not and never has been the private property of the agricultural producer? [In any case, those who believe that the dissolution of communal property is a historical necessity in Russia cannot, at any event, prove such a necessity from my account of the inevitable course of things in Western Europe. On the contrary, they would have to provide new arguments quite independent of the course I described. The only thing they can learn from me is this:] Thus, the only conclusion they would be justified in drawing from the course of things in the West is the following: If capitalist production is to be established in Russia, the first step must be to abolish communal property and expropriate the peasants, that is, the great mass of the people. That is anyway the wish of the Russian liberals [who wish to naturalise capitalist production in their own country and, quite consistently, to transform the great mass of peasants into simple wage-labourers], but does their wish prove more than Catherine II’s wish [to graft] to implant the Western medieval craft system in Russian soil?
[Since the Russian peasants’ land is their common property and has never been their private property.... ]
[In Russia, where the land is not and never has been the peasant’s ‘private property’, the transformation metamorphosis of this of such private property into capitalist property has no sense is impossible is therefore out of the question. The only conclusion one might draw is that .... All that can be concluded from the Western data .... If one wishes to draw some indication lesson from the (Western) data .... ]
[The most simple-minded observer could not deny that these are two quite distinct cases. In any case, the Western process.... ]
Thus [the process I have analysed] the expropriation of the agricultural producers in the West served ‘to transform the fragmented private property of workers’ into the concentrated private property of capitalists. But it was always the substitution of one form of private property for another form of private property. [How, then, could this same process apply to the land in Russia to the Russian agricultural producers whose land is not and never has ... whose property in land always remained ‘communal’ and has never been ‘private’. The same historical process which [I analysed] such as it was realised in the West.... ] In Russia, on the contrary, it would be a matter of substituting capitalist property for the communist property [of the tillers of the land – a process that would evidently be quite ... ].
Yes indeed! If capitalist production is to establish its sway in Russia, then the great majority of peasants – that is, of the Russian people – will have to be transformed into wage-labourers, and hence be expropriated through the prior abolition of their communist property. But in any event, the Western precedent would prove nothing at all [about the ‘historical inevitability’ of this process].