I'm also in the 6'3" club and while I haven't done WTP in *checks notes* 10 years, I was happy with it with the old seats in the 747s and also in the A380 on long US west coast flights.
I remember one trip to SFO where I woke up in the morning with some light but uncomfortable back pain, the short ET hop to Heathrow didn't really make it better, but when I arrived in SFO everything was fine.

The outbound 10 years ago had me gate-upgraded to CW which was slightly unfortunate for my bank account on future travels but got me on the 747 upper deck and BA3.