I have a pair in the hawksbill last, and the general consensus is that you need to size up by half for Antonio's RTW stuff.
I did the same and found the fit to be relatively good.
His lasts are fairly narrow with an average to low instep.
As a reference, I wear:
EB 946, 74945 in 8.5
EB 804 in 8
Majority of carmina lasts in 8.5 except Simpson in 9
I took the hawksbill in 9.
The sizing guide on his website is also fairly accurate and easy to follow.