So, I have 3 Wing Sung 699s. I really like them, except for the stock steel nibs. One of the 3 has a 14k nib. That one is amazing. I'd like to upgrade the other two to have gold nibs also.
It seems these nibs are a "standard-for-China-but-not-for-the-west" 32mm in length, and are the same as the nibs used in, e.g., the Wing Sung 629. In other respects they're about the same as a regular #6 western nib. People who are a little more hands on than I am have been able to put, e.g., Bock nibs in these pens by machining off a few mm from the back of the nib to shorten it.
From searching around I see that there are steel replacement nibs available (from Wing Sung and also from Fuliwen), but I can't for the life of me find anywhere that sells just the replacement nibs. Does anyone know where you can get these nibs without having to buy whole pens?