Sorry, but The Exorcist in post-converted 3D would be awful. Better it be remade in Real-3D (with trendy gun-metal grey grading) than ruin the original film any more than it already has been by the Lucasfilm-esque enhancements of TVYNS. The only justifiable change I’ve seen used on any version of the film was the morphing effect on Damien’s possession sequence.
Friedkin’s film needs leaving alone now. Do a TV version, a 3D cinema remake or whatever by all means, but the original should stand alone as it is.
And I’ve been lucky enough to see the film three times in the cinema: once in a battered original print, mono sound, red Warner logo, no morphing, once in the stereo remix version, which added the morph to Damien’s possession, but inexplicably kept the piano wires lifting Regan, and TVYNS when it was released. I hope you guys get to see it in the cinema! 🙂