Books of hauta and min’you scores used to come with a cheap paper fujaku. The numbers on the paper were meant for use with bunkafu notation, the same notation that we use for Tsugaru shamisen.
Most of the nagauta scores I’ve seen use a different system (kosaburoufu notation) based on pitch rather than position, so while a fujaku will tell you where the notes are (i.e. that you are not playing sharp or flat), the numbers will not coincide with those in nagauta scores.
Anyway, Kyle, maybe you could check your fujaku against the following measurements, with the position 1 as the starting point of 0 millimeters. If it is about the same ( I think it will be), then your fujaku should be fine for a nagauta shamisen. A note on the paper says position 1) should be placed a distance of 1 sun 1 bun (33 mm) from the kamigoma.
(edit: There are some formatting problems, but hopefully this will still make sense):
-
0 mm
-
53 mm
-
89 mm
3#) 122 mm
4) 161 mm
5) 183 mm
6) 226 mm
7) 247 mm
8) 277 mm
9) 308 mm
9b) 326 mm
10) 357 mm
11) 375 mm
12) 401 mm
13) 419 mm
13# ) 436 mm
14) 455 mm
15) 467 mm
16) 488 mm
17) 498 mm
18) 514 mm
It should also be noted that maker of the fujaku assumed a certain positioning of the koma - if you place it too far off of their ideal position, your intonation will be off. A quick way to test this, if you have a tuner, would be to see that certain key positions are in tune. To make it easy, let’s say you tune your third string to C, then position 4 should be F, and position 6 should be G. In the second octave, 10 should be C, 14 should be F and 16 should be G. If they tend to be flat, move the koma closer to the middle of the dou; if they tend to be sharp, move it closer to the edge.