I'm 6'2, 215, and I fit in my Boxster just fine. I'm a little tall for the "broomstick" rule, so I might have to get the roll bar extensions if I do anything beyond autocross.
Climbing in and out is an art form - I am learning to pull in closer to the steering wheel so I don't scuff the seat bolster when I slide in.
Go to the nearest Lotus dealer and get in and out of an Elise... and then try a Boxster on again.