327/300 or 327/250 in 1963 Impala. How to tell the difference.

I found this on the web which I think is fairly accurate. I also think the 250hp engines had a single exhaust. The 327/250 and 327/300 had the same cam, pistons and compression ratio. The 327/250 had 1.72/1.50 valve heads, the 300 had 1.94/1.50 valve heads. The 327/250 had a Rochester 4GC carb and matched intake manifold, the 300 a higher airflow Carter AFB carb and matched intake. The 327/250 had exhaust manifolds with 2" outlets and head pipes, the 300 had manifolds with 2 1/2" outlets and 2 1/2' head pipes

Through 1964 all chevy engines with a four barrel carb had dual exhaust, 1965 was the first year to go to single exhaust.