I would say they painted it with cast iron gray enamel, as long as you have it stripped and the remaining is not lifting from the iron you should be fine just hitting it again with the engine paint of your choice.

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