My Recap of the Northern Dynasties should be perfect information for this premise! (The 6th century recap that is!)
I skimmed the relevant posts a while ago when you first posted them, and I noticed that while they do an extremely good job of covering events and specific details as they occurred IOTL, they barely cover the main causes and effects of social, cultural, economic, and military changes (at least for East Asia), which is crucial to creating a coherent scenario. It's certainly helpful to look over relevant posts in order to understand the general background, which is extremely handy for readers when they're reading a TL. However, a writer who is constructing a scenario/timeline has to go far beyond that, as you need to thoroughly analyze why and how specific conditions occurred, then attempt to present them in a coherent and enjoyable manner to readers, instead of attempting to just regurgitate them without actually digging deeper to grasp the greater picture.
In any case, the posts regarding the Wei and Goguryeo solely reference Wikipedia (although I did see other sources for Europe and the Middle East), which is an important first step, but is certainly not the only one. The summary also does nothing to explain the diplomatic relationship between the Wei and Goguryeo, which is certainly understandable given that there is very little to speak of, in part due to the lack of extant sources. However, the developments are extremely crucial to this scenario, as the Wei and Goguryeo would almost certainly wage war with each other that would essentially dwarf the proportions set out during the conflicts between the Sui and Goguryeo IOTL, if not the Tang.
Other states, such as Baekje and the Rouran, need to be covered significantly as well, as they would attempt to curtail Goguryeo and the Wei's influence, respectively, but analyzing these issues go beyond Wikipedia's coverage, as sources generally tend to focus on Baekje's development after 475, while sources on the Rouran are generally rare.