Will Chevy LT1 cylinder heads work on a 350 block?

No, Chevy LT1 cylinder heads will not directly work on a standard 350 small-block Chevy block. The LT1 heads have a different bolt pattern, valve angle, and intake manifold bolt pattern than the older small block Chevy heads. Significant modification or adapter plates would be required, making it impractical and generally not worthwhile.