About 15 years ago at a flea market, I found the first 6 Beach Boys studio albums in mono, in very clean shape, for a buck apiece.
Most of these albums have been presented primarily in stereo in the digital era, so I was stoked to find mono copies. (By 1965, Brian was mixing exclusively in mono, so those albums always show up in mono.)
My CD of PET SOUNDS has both the stereo AND mono version on it. I'm afraid I must disappoint you when I say I prefer the stereo version.
Big Beach Boys fan, by the way. I was into them long before I was into film music.
The stereo version is sadly a contemporary digital remix. They use digital reverb that sticks out like a sore thumb. And the vocal on "God Only Knows" is out of sync with the instruments.
I wish they would have done a good stereo remix, using analog effects.