I had a 401 in my CJ. When we tore it down, to find out why a terrible vibration had developed, we discovered that the previous rebuild job was very shoddy. It was so bad, that we decided not to put it back together.
It had been bored to .060 over. The cyl. walls were slightly scored, so more boring would be necessary, or sleeving was another option. I didn't want to do either.
Other than that, the block was clean, no cracks, and with a 3-row radiator w/clutch fan, and no fan shroud, it didn't overheat.
I told about it on a few different forums. I was willing to give the block to anyone who wanted it, for the cost of shipping. Different guys on these forums were interested, until they recieved the actual shipping price. After that...no dice.
I listed it on ebay and craigslist, a few times. Again...no dice.
That block is now in the scrapyard.
Here's a 401, not too far away from CA....
AMC 401 Engine Block, Crank, Rods, Pistons, Heads, Pan:eBay Motors (item 260511327279 end time Nov-29-09 13:58:04 PST)
I am temporary running a sweet 360, but have since bought another 401 to install at a future date. Once you have a 401, you always want one (...mostly for braggin' rights...)