There is a manual on BAMA;http://bama.edebris.com/manuals/paco/g15/
It shows that P16-302 is the Paco part number but gives no value.
I would guess that the "140" in the marking may be the capacitance; 100-150 pF is usual in a GDO.
If you have no way of measuring L or C you could wind an inductor of a certain L (there are several on-line inductance calculators which will give reasonable accuracy) and try it in your GDO while listening for a whistle in a receiver; it might take some fiddling but you should find a GDO dial setting that "whistles" at a frequency shown on the receiver dial.
For example; 50 pF (probably about half the GDO C) requires 1.2665 uH to resonate at 20 MHz (an on-line calculator tells me this).
Thirty turns of 0.4mm wire spread over one inch on a 0.25 inch diameter former is going to give us close to that (another on-line calculator).
Try something like that in the GDO and see how close you get to the calculated frequency.
If it "whistles" at, say, 23.165 MHz you can estimate the inductance you require to achieve correct dial readings; it's just proportion.
Once you have one range working you can calculate the max & min C of the capacitor (which will include some "stray" C) and design coils for all ranges.
I built a GDO many years ago;http://imageshack.us/photo/my-images/850/photohqe.jpg/
The exercise of calculating & making the coils was very instructive.
Fiddly; yes, but you will know a great deal about resonance at the end!