I'd been casually looking for a set of the "Book" recommended 221/260 valve retainers with absolutely no luck for several years. They are for sure not very common. For something to do during lockdown, I stepped up my efforts and finally found some. And, as is so often the case, when it rains it pours. There's another two or three sets of those retainers out in that farmer's grove. My question is, should I go back and get them, or just let them return to the earth out in the woods?