I agree; you can put off that decision. I'm a tall pilot, too, and each glider is different. If the chute is critical to helping you fit into the cockpit comfortably, the critical factor could be thickness at the top of the pack, thickness at the bottom of the pack, how flexible the pack is, etc. Or it may not be critical at all. Plenty of time to figure out what you need later.

Chip Bearden