I'm not sure about the -12, but I'm 6'7" and fit in a -7A that was built by and for tall people (my dad (6'5") and I). There are three piano hinge pin positions you can use to mount the seat pans and we didn't even put the forward two hinges in. We also mounted the rudder pedals as far forward as possible. We also use the bare minimum thickness of seat cushions that provide comfort. We fit, but it's fairly snug - we're not hitting our heads on the canopy, but there isn't room for one of those canopy sliding sun shades above our head.
Jump over to Vansairforce and see if there is someone in your area that will let you try it out.