Common advice for evaluating composition is to look at the image upside down (excuse me, I mean "umop episdn"). So in your case, accustomed as you are to LF ground-glass viewing, shouldn't you be getting the same benefits by viewing the right-side-up image in a prism viewfinder? It sounds to me like you should embrace the challenge.
As an alternative, cognition experiments have established that if you wear prismatic glasses that invert your view, after a few days your brain adjusts and you start seeing that inverted view as right-side-up. So a few days with inversion glasses should be enough to convince your brain that the right-side-up view in a 35mm viewfinder is in fact umop episdn. I'm not too sure that anyone makes these glasses commercially, but a homebrew job shouldn't be too difficult as compared to many of the DIY projects we see on APUG. Try it and get back to us with a report, say I.