You'll loose a little high end response if you go up to a 2.4 H model, but that's the same value as a stock Fender single coil, so the difference is not huge. Those 450's are gems, just like your 600.
I have a BL-DXR - basically an enclosed 450 without mounting tags - in my steel string. I can't really recall, but I belive it's a 1.0 H model. It's the sweetest sounding pickup you can imagine. For fingerstyle players in any genre or jazzers who prefer a clean, crystaline sound, it's spot on!