It's an interesting premise, however it probably would have been impossible.
China - which has never come even remotely close to doing the lionshare of US manufacturing [1] - required enormous capital to be invested by US (and European) companies to build up their manufacturing base. That capital needed to exist first before it could be invested into Chinese factories. The US got dramatically richer from 1950 to 1970 (GDP went from $280b to $1t, during the strong gold dollar era), while it dominated global manufacturing. The wealth it built up in those decades of manufacturing hegemony is what in part enabled the US to deploy such immense capital into China in the following decades.
The US wouldn't have had the accumulated wealth and consumer base to utilize the USSR as a manufacturing offshore and make the necessary investments, minus the post war domestic manufacturing boom. Unless we're talking about doing that at the very end of the USSR in the late 1980s, after US manufacturing had already peaked and begun to decline. (obviously this is all fantasy, because the USSR's policies would never have allowed for the scenario, but it's an interesting thought experiment regardless)
Also, given the USSR's population ratio with China (~260m people in the USSR versus 980m in China circa 1980), it would have been impossible on a more practical basis, for them to output so much. The USSR's economy was never known for having world-class efficiency and scale of output. They never mastered high quality massive scale manufacturing. I'm skeptical the bureaucracy would have ever made it possible. It's likely they couldn't have output but a modest fraction of US manufacturing needs under any scenario.
[1] US manufacturing output was about ~$2.1 trillion for 2018. Imports from China for 2018 were something like $560 billion. Approximately a 4x difference.
China - which has never come even remotely close to doing the lionshare of US manufacturing [1] - required enormous capital to be invested by US (and European) companies to build up their manufacturing base. That capital needed to exist first before it could be invested into Chinese factories. The US got dramatically richer from 1950 to 1970 (GDP went from $280b to $1t, during the strong gold dollar era), while it dominated global manufacturing. The wealth it built up in those decades of manufacturing hegemony is what in part enabled the US to deploy such immense capital into China in the following decades.
The US wouldn't have had the accumulated wealth and consumer base to utilize the USSR as a manufacturing offshore and make the necessary investments, minus the post war domestic manufacturing boom. Unless we're talking about doing that at the very end of the USSR in the late 1980s, after US manufacturing had already peaked and begun to decline. (obviously this is all fantasy, because the USSR's policies would never have allowed for the scenario, but it's an interesting thought experiment regardless)
Also, given the USSR's population ratio with China (~260m people in the USSR versus 980m in China circa 1980), it would have been impossible on a more practical basis, for them to output so much. The USSR's economy was never known for having world-class efficiency and scale of output. They never mastered high quality massive scale manufacturing. I'm skeptical the bureaucracy would have ever made it possible. It's likely they couldn't have output but a modest fraction of US manufacturing needs under any scenario.
[1] US manufacturing output was about ~$2.1 trillion for 2018. Imports from China for 2018 were something like $560 billion. Approximately a 4x difference.