The test is can you clear the top tube with cycling shoes on. I would guess if you barely can without you can with. You may even consider mountain shoes for that reason. If you have an inch you are fine.

Reach is another matter. 6cm is short for a stem, 8-9 cm would be better if you could be comortable. If you could also shorten the reach of the bar that's even better than jus the stem. The bontrager fit, salsa poco, and 3T ergonova are some popular choices for short reach bars. I use a 9 cm stem with an ergonava bar and love it.