how to id cast crank 340 flywheel

i pulled this 73 340 and 3 speed apart today and there's small holes drilled in the very outer edge...but no big ones like i expected.how do i id this?

casting number is 2264598

i didn't feel any vibrations when i ran the 340 so i think it's right but couldn't find anything definite.

i just don't want to sell or use this flywheel until i find out what it is.