You can bevel it back with a Dremel tool and a little round grinder attachment. You just want to make sure it cannot snag a ring. Can't imagine any change in port timing would be significant.
Personally, I run a ball hone up in them a couple of seconds both ways with some WD40 sprayed on it. Wipe it out with a rag and you can get a better idea of what you are dealing with transfer and scratch wise. Then if you think it is transfer muratic acid will help desolve it. Carefully with a Dremel and a maybe 80 grit flapper you can get the aluminum out.
When it is all said and done you can see if you are satisfied or not. If you don't like the looks of it junk it. If you can get it slick as a baby's butt put a piston in it and go.