Any thing modified is subject to break...🤣90mm bore is no small task. Most people settle for an 87 or 88mm bore to keep some reliability in the block. A sleeved block at 90mm is one hone job from being scrap.
Besides all that. Over or under square has little bearing on the ability of an engine to rev high. Stroke length is the ultimate factor.
By all means I'm excited to see the n/a 400hp build. It can be done. You might be methanol to get you there but it can be done.