Hi -- please go to this forum
http://www.quiltingboard.com/vintage...thusiasts-f22/ and copy and paste your question again. There are a few people, esp manicmike from Australia, who know a lot about the 319. I bought one myself just a few days ago.
There are pros and cons regarding altering your existing bobbin case. You could possibly buy a second one to alter and use with the shorter needles. However, some say you also need to change the timing, and that is not such a good idea. Anyway, Mike is the guy to ask. :-) . He had his bobbin case altered with no ill effect..
I did see some size 16 206-13 needles somewhere today but I believe they were $20 a pack.
http://www.ebay.com/itm/206-x-13-nee...item339be6f355
See you on the other forum :-)