I think distilled water is expensive, inconvenient and unnecessary. I would flush the cooling system real good (maybe twice) with a product from the parts store. Be sure to rinse good. Run some antifreeze to keep it from rusting. Make sure your nose is sealed up good. I put on a new stock fan clutch and I think I used a fan from a New Yorker or something that looks the same but is 1" larger. You can only do this if your motor mounts are tight to keep the fan from hitting the fan shroud. It won't run hot when you get done.