Update: I've been thinking about zipper pulls off and on for a while since I posted this thread, and I've actually put together a pretty solid collection to go on current and future jackets. I figured I'd show them off, just in case it gives people some ideas.
First, in Bianchi's Flight Gear 1942-1945, I saw that 4-Leaf Clovers were common. A serendipitous eBay search turned up this:
I was on the lookout for some lucky dice, and wasn't having any luck (luck? Get it? Ok, I'll get my coat....). Then I saw a picture
@Thomas Koehle posted on instagram with EXACTLY what I was looking for - it could have come off an original. I asked him about where I could find one and, being one of the great gentlemen of the VLJ, he sent me a pair of dice. Many thanks, Thomas!
Finally, for a Korean War zipper pull, I've been gathering 2-3 Japanese coins. Search for "Japanese 5 yen coin" on eBay and plug in a year from 1948-1952 and you can find a lot of perfect coins for just a couple bucks. A bit of leather lace from whatever craft store is handy and you've got a great vintage zipper pull.