I usually snug the bottom bolts on the perch first, then muscle the upper into aligning with the mounting holes.
That's common, once the shock is removed the way the spring sits on the perch combined with the position of the arm causes the perch to tilt to one side. Especially on a new install where things haven't settled into a normal ride height position yet.
Who cares how much horsepower it has, all that matters is how fast it goes!
Untested 331, lots of suspension, chewing up corners.