Ah, the GLOB at the lowest point of a boiler seam.
I had one like that but it did not leak so I left
it alone.
Don't worry too much about looks. It is not a
million dollar engine, the repair might not be
that visible, and you only have to please yourself.
If the next owner (distant future) is turned off
by the repair, well then they can try to do better.
Anyway, it sure did clean up pretty. I also agree
with you that it must have bn 'cooked' early in its
career. If it runs well, it is a keeper.
Good luck,
Wayne