Magnum swapping the 72 Scamp!

If you have a long rounded rod you can lay it in the pulley groove and see if it lines up with the next one or needs adjusting.

In your opinion how close do I need to get? My plan was to measure from the front of crank pulley face to each groove, then put a flat bar across and measure from the flat bar ( representing the crank pulley face) to the accessory grooves and hope they are close.