Exhaust gasket port size

I was wondering if anyone knew the standard exhaust port size for a 454 BBC. They are stock iron heads with round ports not square. I'm at work ordering parts (I know, 'working hard, or hardly working') so I can't measure them real quick, but the parts place has gaskets for 2.250 and 1.810 inch ports. I was hoping to order them today before I went home so they would be here for wrenching over the weekend, but if there is no 'standard' port size I might have to wait to order them until after I go home to measure. Any ideas?

what year head the new 1999 head has a small er ex port or P ports are rounder .all the big block big O port and Rec iron heads stock are not round BuT there somewhat square all bout the same size .if you have headers you get the header a hair smaller gaskets for the size of tube on the header and if its round on the header flange then its the gasket you run if square then that the gasket you run any other way it will leak