My understanding is that the Magnum block lifter bores are taller than the LA and pose less risk to exposing oil band on the lifter with high lift cams. If true, the magnum should be more conducive to a high lift roller with less block prep. I don't see pushrod oiling as a big detriment using LA heads, and the better selection of intakes makes it worth the effort IMO. Unless you want to run old iron rockers, there are multiple oil-through rockers available for the LA heads and anything approaching 600hp should be using a good quality rocker. There are other options to getting around the head oiling issue with LA heads on Magnum blocks as well. Unless I can fall into a good 340 block, I'll be going with a Magnum for my future stroker.