You just need to make sure to run the right stuff is all. I believe if I remember correctly, the Magnums are balanced a little differently than the LA, although they are both still externally balanced. Just make certain you buy the right balancer and flywheel for whichever engine you choose and you'll be good. The Magnum isn't necessarily "better" however, with fuel injection all it's life and running in an era of modern lubricants, there will be significantly less wear. I've torn some down and still seen cross hatch on cylinders on engines that had well in excess of 200K. THAT'S your biggest benefit. Normally, unless a piston is scuffed, cracked or otherwise damaged, you can run the stock original pistons. The Magnums also had a nice compression ratio of a tad north of 9:1. Now, one drawback is the heads were known to be prone to crack. But still, even with that chance, the Magnum can be a viable option, if you can find one affordable enough. Nothing wrong with the LA, but, you'll likely have a higher machine shop and parts bill, because they are getting pretty old now and won't be in as good a condition.
