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First question related to the valve stem opening. Both were used - the "football" style was the first but its believed that this caused damage to the valve stem so the opening was redsigned to provide more clearance creating the straight side/edged version. Don't have enough data and real build dates to form an opinion or results of a survey to provide a change over date between the two. NOS/service pieces will mostly all be of the later design though The amount of shine or finish on the pieces is another matter and what we see out there is often the results of seeing originals and NOS (service parts) especially on restore cars - all in varying condition I've collected some examples which I will format and post in hopes that this will help you
This is what the correct finishes are on the cap and the trim ring as they were originally. A good stainless shop can fix and replicate these finishes. Trim ring that is correct is shown as well with the correct oval football style. 20220227_163005 by Marcus Anghel, on Flickr