Yes, external balance is stock.
I have an "unknown" engine in my beater car that I snagged off of Ebay.
The main seal leaked like crazy, and when I pulled the pan to replace the seal it was obvious that it had been balanced before.
There are unknown pistons installed that are definitely not stock, although I could not see any markings on the underside to identify them.
The rear main bearing is a .020 under and is not in the best of condition.
I have a set of (ancient) ported irons and a NIB ATR hydraulic cam that I bought in the 90's that I was going to slap on just to see what I can do with the old girl. I figured getting a std turbo crank and having the balance fine tuned would be the most cost effective way of getting some more life out it.