I'd guess the C60 is actually .060 and that is the over bore. The 030 and 010 would be rods and mains but I don't know which. It was probably painted on the aluminum when it was installed.

"It's just a phase. He'll grow out of it." Mama, 1964

1956 Chevy 1/2-ton 3100
1953 Chevy 6100 "The Yard dog"
1954 GMC Suburban Now with a new proud owner.