ITunes For Mac :: Can Re-import CDs In High Quality But Keep Original Track Data?

I got roughly halfway through importing my collection of about 800 CD's into iTunes 12, before realising that the default import settings applied by iTunes is not 'the best'.  In fact it's not set anywhere near 'the best', it's something like 128kbps lossy format.   I wanted to import my CD's in lossless CD-quality.  WAV would have been ideal.  However it would appear I've missed a trick by assuming it would be full-quality unless I specified something else. 

I'm not using portable devices to listen to my music, I have a Mac Mini and an endless supply of hard-drive storage space, and I'm only accessing it at home. 

A large number of my discs are classical and jazz, and in many cases I've needed to amend or reorganise the metadata, so that it all complies with an overall filing and categorising system that makes sense and is useful.   I also have a large number of rock and blues CD's, but their metadata is normally correct when the discs are issued, so they usually doesn't need adjusting.   If you're wondering, yes my taste in music is eclectic.   I'm just as big a fan of Mozart as I am of Motorhead as I am of Mo Foster.   The problem is that with classical and opera it's important that the 'artist' category shows the names of the performer/soloist/conductor/orchestra, not the name of the composer!  (I wish I *did* have actual recordings of JS Bach playing the Well Tempered Clavier!!). 

So I'm looking at this big pile of CD's thinking, "is it worth re-importing them all again at CD-quality?", because I'd really like top-quality copies, and I only really want to have to do this once.   It *is* worth doing so long as I don't have to do all the jiggery-pokery with all the artist/composer data again, because that takes an enormous amount of time. 

So the question is... will iTunes 12 let me re-import my discs at maximum quality, but at the same time let me keep the data that was painstakingly edited and stored with the previous (lesser-quality) versions?   Or is there a workaround?  Maybe I could surreptitiously replace the old audio with new audio when iTunes isn't running and hope that it won't notice? 

Info:
Mac mini (Late 2012), OS X Mavericks (10.9.5)