Could Molotov's hardline against concessions and enthusiasm for state farms/communes make him more simpatico with Mao on policy and ideology grounds, and prevent the Sino-Soviet split?
I suspect that Molotov would get on better with Mao, but any ideological congruence would be a small part of that.
Molotov's advantages towards China come from him actually having some experience at diplomacy and the world outside the USSR - not much experience sure, but a heck of alot more than most people in the Soviet upper ranks had - and from his faithfulness to Stalin (I can see the Soviets under Molotov admitting that some things that happened under Stalin weren't great, but for sure all the school books are going to lionize Stalin like US schoolbooks lionize George Washington, and since Mao sees himself as China's Stalin, he will like that). I don't know if Mao would see Molotov as a strong leader - I suspect he would, but that's not a given. Khrushchev's aura of buffoonery helped him survive and secure power inside the Soviet Union, but when dealing with people abroad, it didn't play well and it REALLY didn't play well with Mao. So Molotov not being Khrushchev will help him there, and Molotov was certainly a strong personality and one who didn't pad his sharp edges in the way Khrushchev did, so the potential is there.
But chemistry between people is often fickle, so it could go either way really.
And as far as policies - what the Chinese wanted (IMO deservedly so) was mainly to be treated with respect and to have their real practical problems addressed. When the CCP won the Chinese civil war, the Soviets were in a race against time to get over their racism and colonialist habits before the Chinese ran out of tolerance - in OTL, the Soviets didn't manage it. The Chinese also wanted Soviet help with their economy and military (which in OTL they largely got - Soviet aid to China after 1949 constitutes the largest technology transfer in human history even though the Soviets said no to a few things) and for the Soviets to address the disputed areas of the Sino-Soviet border as equals, rather than continuing to be as intransigent as Tsarist Russia. Oh, and the Chinese wanted the Soviets to treat them as masters of their own house. The Soviets had broken off most of Mongolia from China and tried to break off Sinkiang from China during the warlord period - with such a history people in Moscow saying what people in China ought to do and how they ought to go about working towards socialism wasn't the sort of thing that was ever going to play well in Beijing.
Maybe Molotov could move on these practical concerns faster due to his diplomatic experience, maybe he wouldn't have the mental flexibility and would continue thinking China was the mess of the 1930s and 1940s until he is smacked in the face by a full on boarder war as Brezhnev was. Maybe Molotov would have worse relations with the west, forcing him to be more considerate and generous to his Chinese allies. Or maybe Molotov's likely conservative (well, conservative compared to Khrushchev) foreign policy and WW2 experience of working with the WAllies would lead to a sort of slow, cautious detente that would enrage the more radical Mao. Maybe Molotov's "Old Bolshevik" cred (he had joined the party much earlier than Khrushchev) will lessen Mao's insistence on being seen as the senior leader in world socialism. Or maybe Mao will still insist that Molotov treats him with deference, Molotov will be too blunt in his reply, and the split is even worse than OTL.
So all in all, I think congruent policy is the icing to a much larger cake. Congruent policy alone wouldn't save Sino-Soviet relations from going down the tubes, and I can imagine the Soviets and Chinese going in very different directions policy-wise, but still remaining close, if fractious, allies.
I DO think that even in the best case scenario, the Sino-Soviet relationship will be a delicate and spikey one. Especially during Mao's day, the two great empires will not find it easy to be friends. But I do think it is possible to avoid a complete breach as occurred in OTL.
fasquardon