440 motor mounts in a 74 dart

If everything fits well like it is and you're happy with it other than the engine not completely level, I'd say leave it alone. You could take the thru bolts out and lower it down a little to see if you need to drill some new holes in the saddles. As long as moving it down doesn't cause you a bunch of rework on your headers and driveshaft angle, it shouldn't take long. I linked the DC K frame instructions above in case you needed to back up and punt.