Seems to me either bending this bracket or using a different one, as well as lowering your struts will get you where you want.
Had the same problem trying to use a VO canti rando rack on my Voyageur. Then I got a Nitto rack and bought longer struts to reach the mid fork eyelets. It now sits lower and level and is near perfect, although a little lower would be ideal. Seems like these racks are made with a certain bike setup in mind, particularly a more modern one, and probably 650b, so they won’t always line up well on vintage roadies out of the box.