Mabie Todd: L330/60 Sac Size?

[TomCorbett]

Found this at the local antique market today: it may be a little rough, but at $25CAD I couldn't resist it as my first foray into vintage pens

 

From the stamp on the bottom (L330/60), I figured it's a pre-war, black hard rubber, size 3 Mabie Todd Leverless, c.1934.

The nib section is stamped with "Swan L3" and the body is stamped with "Patent No. 390585/32".

The nib is #3, 14ct gold, and apparently flexible from a quick dip-test with Monteverde Sapphire ink. It's so smooth and wet!!

Unfortunately the left tine of the nib looks a little bent... but I'll see if I can massage it back into shape.

The rubber sac is totally missing but the pressure bar is present (hard to see from the photo) and the twist button turns well.

Anyone know what sac size this would take? Anyone done a sac replacement on this pen?

Any help would be much appreciated!!