Last night I got the position much better, I ground away a little more material off the lower attach angles (as per the plans) and that seemed to help. The mount is still sitting slightly forward but now a lot less, just under 1/8”, vertical position is now perfect. I don't think I can get the mount any further back against the firewall unless I grind away a little material of the lower attach point on the mount but that could compromise the weld. This is not an uncommon issue and I've noticed on other builders websites that they seem to accept variations of up to 3/16" forward (the cowling comes oversize so that's no issue), so I'm not too worried about this, I've contacted Kerry at Sonex just in case.
