Depends on the conditions of the split and when it happens. Staying friends through the death of Stalin would be different from - say - Mao tripping over a rock in 1951z which would be different from the split getting patched up in the early 60s upon Mao getting fully forced out and Khrushchev replaced.
Regardless of everything else, as China overcomes its early 20th-century issues and moves towards industrialization it's going to be extremely hungry for the kinds of heavy industrial/capital goods the USSR was able to produce en masse. What starts for the USSR as the continuation of 40s-50s industrial aid programs probably ends up as a significant export sector for them. China is also a strong market for Soviet energy, especially as it develops.
At the same time, China not being in a condition of total encirclement and economic isolation means that desperate shock tactics like the GLF and collectivization are less likely to be carried out. This is especially true given the power of internal factions turned off by Soviet shock industrialization and heavy industry fetishism who consistently called for a better-adjusted, more "even" approach. China likely develops in a far more consistent, pragmatic, and "orthodox" developmental direction - less Maoism and no Dengism, but probably way more Chen Yun and Li Shaoqi. Still planned, but more in keeping with both the party's general preference for an even approach which includes the countryside (a source of many of Mao's more "clever" ideas) and the pragmatic faction's attachment to planning as a moderating and rationalizing tool rather than a way to produce radical breaks. This also probably means far less famine and more grain available for export.
The USSR basically halves its hostile frontiers, allowing more military concentration in Europe and the Middle East or less spending, and has a far freer hand on the international stage. It also means that the US can't play China off against the USSR to triangulate pursue detente, so you probably get a more militant posture from both. However, I also suspect it leaves India more clearly in the Western camp. The Communist world is also likely going to be less thoroughly Soviet-dominated, possibly opening up more spaces for independent alternatives.
It's hard to say and depends on the exact details, but a Sink-Soviet friendship persisting, at least in terms of economic cooperation and basic military/diplomatic amity, has immense advantages for both through the span of the Cold War.