1AB have a cutout under the bulkhead, which give you 40-41" of room. I am 6' 2" and find it plenty. 1CD have no cutout so you get the straight 38" and it is darn tight. On an empty 757 I was 1C and moved back to 6C during the flight just to get some legroom.

2-6 are 38", but you get an extra inch or so of underseat space (the entertainment system boxes extend across the seat and block most foot space). And someone who reclines back will intrude on your space, as well.

I still recommend you keep 1A.