Those heads are poor on the exhaust flow compared to older heads. I have heard they are a thinner casting in some areas, but can't confirm that.
You have better choices in the 5 6 7 castings and even the 8s are better than the 3A, as is. So, yea try to find another set.
But in all honesty, If I was on a budget and had a good set of 3A heads, with nothing else stopping me......I'd run'em. Oldsmobiles are more fun when they're running
.........than sitting around waiting for whatever.