I know yer not a EBCF fan, but my #2814(45/65/80/100-medium tension)set is really working on the 67 NR. I played a gig Saturday night and even using the R200c(15"), E wasn't at all 'boomy' and D and G still had plenty of 'oomph'. I've thought about trying a LPF/HPF, but I'm already running too many wires underfoot, especially when I provide PA. I see Broughton makes a battery powered one, but, TBH, I don't have an 'extra' $165* laying around. Guess I'll stick with EQ'ing the amp.
* mufunzalo. Still.
('course I'd have the $ if I sold the NR for anywhere close to what it should be worth, but that would kinda defeat the purpose)