No, BA295 will not work with my connecting flight from OSL
BA49 LHR-SEA will work but I could not book this as it was much more expensive than flying via ORD.
Your comments are exactly why I'm concerned about this connection - even if BA297 arrives on time - I also have to change terminal at ORD

I have been to ORD before and it seems like taking forever to pass through US immigration (I don't have Global Entry).