making it lighter , flywheel Options

[pxcr440]

i have my cars motor completeyl stripped down and gunna put it back to gether soon and i was considering the fly wheel , a machin shop said they could turn in down on a brake machine , well the back of it , i just wanna know if that would work cause i have access to machines at school and was thinking that i could take off some weight and not sure how far t o to turn it down