I'm 6'4" and 220 lbs. No issues fitting in mine.
When going taller than that, legroom might become an issue, I'd think 6'6" max??. Without cushions, I would not even come close to looking over the cowling properly, so plenty of headroom to work with.
When going larger than my 220 lbs (broad shoulders or slightly below that), I really don't see any issues. The thing is surprisingly roomy.