I think the block is the same through all of those years, the difference between the generation 1 and Vortec is in the heads so the mounting holes on the front of the heads may not line up. There are many serpentine aftermarket mounts available to position accessories in different positions.

1957 Chevrolet 5700 LCF 283 SM420 2 speed rear, 1955 IH 300U T/A, 1978 Corvette 350 auto, 1978 Yamaha DT175, 1999 Harley Davidson Softail Fat Boy