Sounds like a vacuum leak at the intake, or somehow you're restricting the water flow from the block to circulate thru the heads. Is this a jet? Any water valves not open?.....Or not closed?......No one messed with the heads, right? Same heads, same block, the only things that changed were the gaskets........Sheet metal or aftermarket intake gasket?........Maybe some of the Olds experts here can tell you if there are more than one type head gasket.....I know some Fords changed the water routing from block to head........Maybe Olds did too.........MP