There are lots of "what if's" to consider when planning the reroof. Assuming you will be installing roofing that has the ribs running parallel to the rafters, it could sag between them and look wavy. Snow and wind load capacity are also major considerations.
Besides lowering the ridge beam/ledger board, you could install flat bar or angle over the existing rafters to add horizontal strength. Naturally, each solution has its own set of advantages and challenges. If you live in a municipality where codes and permits are in play, you can always ask the building inspector whether or not a method will be allowed.
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