HELP figuring cam lift ( maybe actual purple shaft p/n?

The cam grinder assumes the rockers will transmit the correct ratio to the valve. So if the cam is sold as having 0.450" valve lift, with 1.5 rockers, the lobe lift will be 0.300" if the cam has been accurately ground.
Is the cam new or used? If used, & lobe peaks are worn, it will be hard to work out original lobe lift.