Brutal 6 Racing
Here's my speculation in regard to the block which has 0198U1283 written on it in paint pen. It most likely is the first 197 cast block. The 0198 is January of 1998 and the digits following the "U" are a sequential number from Uni Boring who did the machine work on these blocks for GM. They probably used the machining program they had from the 153 block casting for the first one which is why it is 1283. When other 197 blocks came thru their shop they likely started at 001 and continued. We'll never know for sure, Uni Boring went bankrupt at some point around 2008.