If you really want the original originals from a totally pure source, you’ll have to go with TN1’s Silver Screen edition for the original and the Grindhouse editions of the sequels. Those are all 100% sourced from 35mm film print scans. The problem is the “grindhouse” releases haven’t been cleaned up yet, so they’re pretty grainy and scratchy and have some color issues. But they’re 1080p and the only versions that can rightfully be called “theatrical.”
Still, if you want something that approximates the Blu-Rays in terms of crisp clean image, Despecialized will definitely satisfy you. You won’t notice anything that might not have been restored unless you’re the most hardcore of the hardcore nitpickers who know each and every frame by heart. If you haven’t even seen them in a long time, then I can assure you nothing will be different from your memory at all.