318 race engine 4104230-318 any info. on these engines?

I know for sure I read somewhere that these engines had flat top pistons in them...though I can't find that source and if that was so it seems they'd be more wanted....

Anyway, a little searching yielded this:

which can be found http://sittingfox.tripod.com/smallblkcompare.htm just scroll down half way...the the 318 is the cui and the last number the replica of the origional cast i believe....

1981-’84 CAR AND TRUCK
This block was identical to the earlier one except that the hole for the brace on the left side was moved forward one inch (to 10˝) so that it would clear the bigger starter motor. Most of these blocks had a boss with room for both holes, but they were not always drilled. These engines all came with flat tappet cams. Look for casting number 4104230 or 4179730.