Beautiful piece, well done. I especially like the layered arrangement; every part clearly owns its own space in the mix. Pad works well on my monitors. If you're "happy enough" but not overjoyed with it, lots of things I would try in a similar situation.
To avoid distorting due to an EQ boost, I'd try the reverse, reducing everything except the boosted area, so that freq balance changes without overdriving the signal.
Parallel tracking is a possibility, duplicating the track and then hard cutting everything except the boosted freq band, which is indeed boosted--then gradually mix it back in next to the main track.
These days I tend to 'cheat', using some plugins that emulate vintage gear for subtle sweetening just from the character of the modeling--LA-2, Fairchild, Pultec. And Sonar X2's Prochannel desk emulators (bottom section) seem to help, in an even more subtle way--this part I'm still trying to figure out how to get the best benefit.
[ File under 'More than was asked for' ] Musically, I think I've heard all the material this piece has to offer by about 2:20. At that point I was expecting the piece to do something melodically/harmonically/texturally different, as a departure from what had already been set up. Even just 8 or 16 bars of some really new element would then give the chance to bring the piece back to its 'home' material at the end.
Just some thoughts on what is already very fine work, thanks for posting it!