6' in a Voyager 35
I am 6' and live in a Voyager 35. In the saloon I have just enough room -- barefoot. If I have shoes on or winter boots, my head will rub. There are also a few things mounted (handholds, instrument cluster, etc.) whose locations your body gets to know intuitively after several head bangs.
Of course you will need to visit (and survey) a boat before you buy, but I can see narrowing down the choices from specs could be very frustrating.