I've done a couple motors with the MRL's and they look like they should clear but it's been a while since I had a Magnum block in front of me.

They will pushrod oil with no problem so they should be a good fit for the Magnum heads. In fact on my 59 degree 70 340 block I've restricted about 95% of the oil through the block. the .815 diameter rollers with direct oiling are a nice feature plus they are strong and light. I replaced a set of Morels on my 414 with the MRL's and they were about 3 ounces PER PAIR lighter.

Here's a pic, they look like they'll have plenty of top side clearance.