The beginning and course of the war is gonna rather heavily impact this. A peace treaty in which American political will breaks after the Red Army drives them out of Eurasia as the result of a an ill-conceived attack on the USSR is going to be extremely different then one which the WAllies/NATO drive the Soviets back into Eastern Europe after a few years and several million WAllied dead but decide not to go the extra mile in heading on to Moscow during a war whose beginnings arose from a complicated crisis which in turn will be extremely different then one in which the WAllies drive the Communist Bloc to collapse during a protracted war after a unprovoked attack. And those are only a sample of the myriad forms with which WW3 could occur and unfold in the '45-'53 timeframe. With that said, since the OP specified a total WAllied victory scenario, presumably by driving the USSR to collapse after a protracted and bloody war, I'll focus on that for the rest of this post. The place to look to gain some indication of American peace intentions would be US planning for war in this period.
The first American war plans of this era, the 1946 Pincher-series, didn't contain anything in the way of political objectives in the event of victory as that plan was almost entirely focused on the first 18 months of hostilies, with only vague thoughts given to the later stages of such a war and none at all for the final outcome. The 1947-48 Broiler-series of plans was the first to address any sort of end-state settlement and envisioned that, in the event of total victory, the peace settlement would involve the retention of a unitary Russian state within the 1939 borders and the disarmament of said state, but was a bit vague on further details largely because the planners lacked any political guidance...
In the absence of a definitive policy statement from the civilian leadership, the planners assumed that the US would seek to destroy the war-making capacity of the USSR to the extent that the Americans could compel the withdrawal of Soviet political and military forces at least to within Russian 1939 borders. It was not clear whether or not the Soviets would be required to relinquish territory taken from Poland in 1939, but the planners obviously expected the Baltic States to regain their independence and presumably Finland and Rumania would regain territory lost in 1940. The planners also assumed the United States would create conditions which would assure the abandonment of Soviet political and military aggression. Whether or not this meant the overthrow of the Communist regime or merely the installation of a peacefully inclined Politburo remained unclear.
-American War Plans 1945-1950, Steven T Ross, Pg 62.
The above political assumptions were largely retained in the subsequent 1948-49 Bushwhacker-Halfmoon series (although Bushwhacker at one point rather bizarrely denied the idea of forcing unconditional surrender, despite the fact that it is difficult to see how else such political objectives could be achieved). It wasn't until the 1949 Offtackle-series of warplans that the planners received any sort of political guidance to alter and refine their thinking for a political settlement in the event of total victory. This plan did call for the break-up of the USSR, but a core Russian state would be allowed to exist so presumably the division would be done along the lines of making the 16 Soviet republics independent. While a communist regime might be permitted to exist within the territory of the RSFSR, it would do so in a disarmed and peaceable state. Plans after the Offtackle-series (such as the famous Dropshot-series) largely stuck to these ideals.
Offtackle was the first plan that contained authoritative political guidance. NSC 20/4 established American objectives toward the USSR. Political goals in both peace and war were identical--to reduce the power and influence of the USSR to limits which no longer constituted a threat to peace and the independence of the stability of the world family of nations.
War aims supplemental to peacetime goals included the elimination of Russian domination in areas outside the borders of any Russian state allowed to exist after the war and the destruction of the network of relationships though which the Communist Party of the USSR exerted influence over groups and individuals in the non-communist world.
The United States also intended that any regime or regimes on traditional Russian territory would not have the requisite military power to wage aggressive war. Additionally, if any Bolshevik regime survived in any part of the USSR, it would be denied the military-industrial potential to be able to wage war against any other regime or regimes existant on traditional Russian territory. These goals were to be pursued without permanently impairing the American economy or way of life.
-American War Plans 1945-1950, Steven T Ross, Pg 111-112.
Of course whether that final requirement could be fulfilled during and in the aftermath of a WW3 scenario is... debatable.