I've already made this TL with regards to a Russian base in SE Asia, though that is the TL that I wanted to rewrite. Anyways, perhaps an extension of the Muscovy Company which would be in charge of managing trade with the Orient would have to be created, and also the condition for a Russian presence in SE Asia is that the British cannot have any colonies in the area, even including India. Why? As long as the British have a presence in South Asia, they would do everything in their power to get rid of any potential competitors, including the Russians.
There is a reason why I chose a minor PoD in 1547: to find a way to butterfly the Livonian War, which broke out because Russia was trying to get a Baltic port when I came across a portion in wikipedia that the German agent who planned to bring 100 builders to Russia was arrested IOTL. That PoD was that Hans Schlitte doesn't get arrested, brings the builders to Russia, and rennovates the neglected port of Ivangorod, which is how my thread 'Ivangorod Prosperous' came to be. For India, originally I was going to have it partitioned between an independent Prussia (I wanted to try out a German India scenario) and a second Ming China.