I think it's neat that the needle shape is a decal on the bed! There is a guide on how to grind a 15 x 1. They eye has to be at the right height -- the overall length is not as important:
http://myperfectstitch.blogspot.com/...r-classic.html
This Free-Westinghouse looks a lot like yours and this fellow also grinds down needles:
http://thinmansewing.blogspot.com/20...d-me-home.html
I wonder if you can use a too-short needle (like a 24 x 1) and experiment with not sliding it all the way up into the needle bar.
Here's a needle chart from ismacs:
http://www.ismacs.net/needle_and_sha...lat-shank.html
Nice finds!