I'm 6' 7" 200# myself. I haven't sat in the -14, but have flown both the -7A and -10 quite a bit. The -10 is infinitely more comfortable than the -7A. I don't remember the dimension difference between the -7A and -14 off the top of my head, but I think the main difference is the cabin width, which would be very beneficial, but still wouldn't compare to the -10.
For the -7A, you have to 'slide' down into the seat and once you're in, you're in. With the -10, there's definitely more room to shift your weight/legs around a bit when you get a little restless. Also, with the -7A, we didn't even install the forward two positions of piano hinges on the bottom seat pan - we just installed the seat pan as far back as it will go. We also use thinner-than-most seat cushions. They're not bad at all - actually pretty comfortable - but they're not as 'plush' as you may see with other seats. Even with these changes, my head is about 1-2" away from the top of the canopy.
With that said, I have done several long flights in the -7A -- Iowa to Las Vegas, Iowa to Boston + NYC, Iowa to San Antonio -- and it wasn't torture by any means, but once the -10 came along, the -7A got relegated to 'fun' plane and the -10 took over cross-country duty.