Socialism in One Country isn't against Marx at all. The argument between Socialism in One Country and Permanent Revolution was whether it was worth building up Socialism while also supporting global revolution, or devote all resources to global revolution and give up on Socialism until then. Permanent Revolution ended up being generally wrong, and depended on the Peasantry being incapable of genuine alliance with the Proletariat, which was wrong.

Genuinely, what do you think Socialism in One Country means to where it goes against Marx? Communism must be global, but Socialism begins with the Proletariat taking control.