Well Mike, I bought the bike new and those are the carbs that came on it. I know they haven't been switched and the slides and needles are original. I have changed mains and idles over the years. But I'm glad you said so because I just checked my 4 unopened NOS needle jet/jet kits 16012-392-004 and they also have 271307 needles in them. The jets have no markings on them. Would this bring you to the conclusion that the jets are all identical but the needle is the difference?
correction: I was asked to double check the needle number. I do not have time to remove a carb from the rack again now but I did remove 1 needle from the NOS package. Upon closer examination outside of the package with a magnifier it turns out to be 271307. I WILL take another look inside the carb too.