Last March I suddenly heard a loud clatter coming from the B18 in my 66 1800S. That was the start of a two month odyssey once I decided to rebuild the engine. It was two months of stress and searching for parts, one trashed friendship, dealing with a Neanderthal machinist, and almost a thousand dollars in overruns.
But, it's all over now and my B18/20 is a sweet running motor that I enjoy almost every day. There is life after these rebuilds.
If it's not too late to have the engine balanced, do it. Upgrade seals to have a dry motor. If you suddenly have compression you will probably need a starter before long. The list goes on.
IPD seems like a good company but sold me the wrong parts once too often. There are plenty of other suppliers out there.
Good luck.
Bob
66S