Which 360 Block to use: LA or Magnum?

The Magnum heads have small, closed chambers for quench and 1.6 rocker ratio. Magnum blocks have a shorter deck height for better compression. They also have roller camshafts. Their only down side, if it is one, is that they have pedestal mount rockers. Although Hughes Engines makes some REAL nice roller rockers for them.

I don't think I would ever build another LA. Not because the Magnums are necessarily better, but because of the excellent wear characteristics. I've torn down a lot of them and so far, I've not seen one without cross hatch still in the cylinders.