I am 6'3" but I have a very long back and sit like I am 6'5" or 6". I
have tried many sailplanes only to be very disappointed. From
previous comments I have found that the common recommendations like
the Mosquito or the Standard cirrus, discus, ventus, Pegusus, were too
small. The Genesis was OK but the canopy catch hook in the back was
pushing right in the back of my head so it was a no go. The SZD-59
Acro/48-3 Jantar Std3 (same cockpit) I have consistently heard and
believe to be the biggest around. I curently fly a Grob Twin II which
works quite well or a DG 1001. I have heard that the Grob 102 single
place fits just like a 103 and for club class, that might be his best
option. My personal ship is a DG-303 which would work if he has long
legs because you can arc your legs around the instrument panel. My
legs are short for my body, I have a 32" pant inseam. Pilots with
long legs, (34"-36") seem to do better than long backs like me. Best
of luck. Anything by Schleicher will probably not fit as it has not
for me. I can not even fit in a ASK-21. Yes, it was a very sad day
of soaring lessons as i pushed the ASK-21 back to the hanger because I
did not fit, only to trade if for the very humble 2-33.