Mike,
Not sure what you want to achieve - pretty pictures in "different" wavelength colours 0r to use your filters as Photometric filters?
The particular emissions of nebulae are controlled by the local conditions and any intervening dust. Most of the WR/ Be stars as well as nova give emissions due to the interaction of dust/ gas shells, but at the resolution of the filters (30A) you will not record the detail, just the macro intensities, hence the use of Photometric filters and magnitude studies.
As you say, the scientific method is to use a spectroscope - or even a low resolution grating.
Kaler's "Stars and their Spectra" makes a good starting point.
Also check out Richard Walker's Spectral atlas and explanatory notes.
http://www.ursusmajor.ch/astrospektr...age/index.html
(down the bottom rhs for English)