Yes Psycho would still be R, but very soft one.

Nobuo Nakagawa's 1960 film Jigoku is hard-R stuff nowadays and would have been an NC-17 in the nineties. The level of gore is quite unbelievable, well beyond anything Western cinema was doing at the time. Eyes Without a Face, from the same year, is less extreme but still disturbing enough to rate an R today, or perhaps a tough PG-13.
All HG Lewis films from 1963's Blood Feast onward are at least R level. Repeat that sentence for Jos Mojica Marins' Coffin Joe series.
A Song of Love (Un chant d'amour) is a 1950 silent by Jean Genet that is absolutely 100% guaranteed an NC-17 if the MPAA ever see itwhich they won't.

http://www.imdb.com/board/10024894/board/
I haven't seen it, but this one sounds pretty iffy for a movie that's almost 80 years old. Satanic cults, a serial killer, necrophilia, drugs, torture, flaying, and human sacrifice. On a list of scary movie moments, Wes Craven said that the final scene (a barely off-camera scene where the hero slowly skins the villain alive, shown in shadows) made him feel sick to his stomach. WES CRAVEN!
Psycho is officially an R, but it was rated that YEARS ago.
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"Fine. You want to eat? Let's see if you can eat PIZZA!!!"

A Clockwork Orange would most likely still cause some controversy, if released today. That was 1971.
However, a movie that came out just two years earlier that had similar controversy, Midnight Cowboy (which ended up winning best picture at the Oscars, despite it's rating) would most likely be rated much more mildly today.