Unsure, have you checked the internet movie database? Phsycho was on ITV last week broadcast widescreen (the first time I've seen it like this), like you say it's probably no wider than 1.85:1 and they showed it 16:9 as it seems is convention.
AFAIK....1st film is 1.78:1 anamorphic; 2nd film is 4.3 full frame (no idea if it's open matte or cropped, although according to IMDB the OOP R1 is pan & scan and I suppose they could have used the same master for this R2 disc); 3rd film is 1.85:1 letterbox (the same as the old OOP R1 edition, which I have) and the 4th film is 4.3 full frame (filmed in this ratio for TV, I think).
I've been hoping a better release of Psycho II would appear by now, as the original R1 release has been OOP for quite a while. But nothing on the horizon yet. I think the film deserves proper treatment on DVD...documentary, interviews and in particular a commentary from Richard Franklin would be most interesting...I'd like to know how Franklin approached making a sequel to one of the most iconic horror/thrillers of all time.
Bumping this thread because - at long last - Universal are re-releasing Psycho II & Psycho III this September in anamorphic additions. No other specs/extras detail yet, but great news for those of us who've been waiting for Psycho II in its OAR for what seems like an age.
So glad I didn't give in and buy the R2 Psycho Collection box set from Amazon like I almost did last week.