I have a 8 man Viking commercial raft that is approximately 10 years old. It has been sitting in my garage for 4 years. I will let it go real cheap to anyone who is interested!....oh yeah its unused! LOL
You generally can't repack a non-solas raft to make it solas compliant. It's not just the flares, its how the raft itself is built. They use heavier fabric, different ballast, different boarding aids etc.
You pretty much have to start with a solas raft. You can't upgrade the packing list and put a new sticker on.
Though there are some who will just apply stickers.