I hate to bring it up all the time, but tis a shame you aren't playing the 60Hz version.
Well yeah, but thems the breaks. I actually have a quasi-solution for 50Hz on my television. It does nothing for the speed, but if you have a game with an unoptimized resolution (i.e. the game uses none of PAL's extra resolution and introduces the black bars), which is basically all PSone games - put your TV into 14:9 mode if you can.
In 14:9, all my PSone Classics look perfect full-screen. Not stretched into widescreen, mind. It's as if you have a full-screen 4:3 presentation, with perhaps an ever-so-slightly stretched width. Works wonders, highly-recommended! Doesn't do anything to the speed, like I said. But it's something.