Reeldoc
A-2 is a good steel for big knives, lots of maintenance (read RUST).
Contrary to what Lizard says, D-2 is not only for small thin blades. The Walter Brend 8 1/2" model 2 in 1/4" D-2 served me well all around the world.
The steel you are looking for on a large blade is 3V, now in a new stainless version (but limited in thickness as of today).
The A-2 version will serve you well (keep the blade oiled).
D-2 will be better. I base this not on a internet search or what someone told me or what I read. This is based on actual use by me.
Keep the RC at 57-59.
3V may be better, but requires a little more maintenance than D-2.
When you are discussing big blades, you leave out ATS-34, 154CM, 440C, BG-42, 420V, 440V, Talonite and Stellite. As they are either inferior, not available in the size you need or too expensive for the size you need.
I don't thing Trace works them, but 1084 and 1095 carbon steels are excellent for big choppers. Again, lots of carbon, little chromium, means lots of maintenance or lots of rust.
No matter what choose you will be very happy with any knife Trace makes you.