Here's how I do it.
I use a credit card or other small straight edge and lay it across the couplers at 2 points ~90 degrees apart from each other with a small flashlight behind it and leave the dampener out at first. If there is a gap, you'll see it and you can tell whether the engine needs to be moved or angled. Once you get it flush on both couplers on both sides, you're set. Note where it is, pull the engine to stick the dampener in then put the shims back in and recheck.
I will say that having Kawi style billet couplers and Wammer mounts makes it a little different from oem mounts/couplers but it's the same process.