At least in Unit one in AZ, we look at the 3rd's and 5th's. Usually one is short and the other long.
If this is the case in Alberta, make sure the 3rd's and 5th's are nice and long. If one is short, think twice unless you know he has it everywhere else. Soetimes its easier to tell a long or short 5th than a long or short 3rd.
In any event if the beams sweep back and that back fork is long and deep, you have a good starting point. If those fronts look as long as the nose like casey said and kinda have a nice sweep up, that is also good. If you got both of those and that 3rd point looks as long or close to the first two, thaen you got a solid bull.
Look at mass aswell. That big bull will carry it most of the beam.
The best thing you can do and should do, is contact a taxidermist or a few taxidermist in Alberta. Ask them what the average 350 bull has as far as tine length, beams and mass. As him for pics of those big bulls and measurements if he has them.
I did this when I was starting to field judge coues deer. My taxidermis said most mature coues deer have 15 inch beams, 22 inches of mass total, and about 14 inches inside. So I start at 52 (beams and mass), look at ears and guess spread, use ears or nose to guage tines. That saves me a lot of time field judging.
Contact a taxidermist and find that stuff out for the area you will be at. That will save you time and also help you tell that 320 from 350. I am sorry, but after a certain size big is big untill you hit that 380 mark where the oh poop factor sets in and you know he's a monster and who cares score.
Good luck and I hope you share some pics from your hunt and God willing success.
Kique
