If you get an aftermarket camshaft intended or sold as a Magnum camshaft, and it specifies it has been drilled for LA head oiling, like many of Hughes Engines cams and some others, you'll have NO issue with insufficient oiling from the camshaft.
If you were to re-grind a factory Magnum camshaft or buy an aftermarket camshaft that is NOT drilled for LA oiling, it will starve the shafts and rockers of oil. You'll need the rockers like those mentioned above with pushrod oiling provisions, or do an external oil line to feed the shafts.