Obviously the magnum block is missing the oil feed for the LA head. That being said, you will be limited in head choices at that point unless you are willing to pushrod oil a LA head (which then limits rocker arm choices).
I think what it comes down to is, see what heads are out there that could fit your goals, and decide if you need a solid roller to get there or not. That will guide you which block to use.
You do have other options also, if you really think the newer blocks are better, the 85'ish to '92 LA blocks are more like a magnum with hydraulic rollers, but still feature the oil feed hole for the heads. I have a '91 block in my turbo car, and it has a factory hydraulic roller setup in it, but LA heads.
THE Earlier magnum blocks were still drilled for rocker shaft oiling. I think up to 95/96 years
I agree I have the indy cylinder head intake for a magnum on my 360. But I had to have the indy intake drilled for the L/A head bolt holes, when I switched to the trick flow heads. I am useing PRW 1.6 billey steel Rocker arms with a comp cams 550 solid lift and push rod oiling.
