Arthur, those room dimensions(assuming about an 8' ceiling)aren't anything unusual and wouldn't result in more than the usual(often substantial)problems with room modes. If the new room has more rigid walls(e.g., plaster compared with drywall)this results in louder bass because of less absorption by wall flexibility.

Speakers should be positioned so that the centers of their woofer cones(not the enclosure)aren't equally distant from the three nearest room boundaries(floor, side and front wall). This to prevent reflections from those boundaries from piling up at the same(especially bass)frequencies. Your present distance about 15" from the wall behind would be about 36" to the center of the woofer cones.

Parametric equalizers(included as manual options in some HT receivers which have auto room EQ)are relatively crude processors compared to advanced room EQ systems. There is(was?)a separate Audyssey SEQ room equalizer sold to professional installers for about $2500. The current most advanced Audyssey MultEQ XT32 version available in HT receivers apparently has similar capability.

At this point I'll repeat a suggestion that I've made to you in the past: the concept of listening to 2-channel music sources(especially the thousand or so classical CDs that each of us have)only through front speakers is badly dated and doesn't allow the ambient sound(from directions other than direct frontal sound)that was mixed into the front channels(there was no place else to put it)to come from the surround speakers where it belongs. Extracting this ambience from the front channels with a mode such as DPLII in a modern HT receiver and directing to surrounds(preferably QSs)contributes significantly to listening realism and enjoyment, and I'd never voluntarily limit myself to listening just on front speakers when I had surround equipment available.

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Enjoy the music, not the equipment.