I am 6'4 - and as an IP I was 220 lbs. I was scrunched over a little and I could have used and inch more forward in the pedals - but even flying 6.5 hours per day I was fine. Big guys need lumbar support - so save your back. Keep up your PT on core strength to avoid back issues later on in life.
I can tell you every fleet and production helo I flew was a non issue. The most spacious seat I ever flew was the BK-117.