Need help with front crossmember coilovers??????

[low69chevy]

Like title says im working on my 69 c10 took out all the whole front suspension complete and ready to install the new scotts hotrods coilover crossmember the thing is its a weld in kit not a bolt on so they told me to move it 1in foward from the original centerline so the wheel can be centered the thing is i already took out the suspension so how can i figure out where to get my measurement from is theyre a marking or a certain hole on the chassis i can use as refrence to start measuring if not the last option i belive is going to build the a arms and everything and try to center it that way by the fender. Any advice would help thanks in advance