If you read the post you'll note I commented that these mods are total overkill for any but the most aggressive, high rpm (7K plus), or extended full throttle at 6K plus like in road or endurance racing. You DONT need a 5/8 pickup because the top end doesnt need a large volume of oil, and the lower end isn;t being built with the wide clearances that require a ton of oil either. As noted - the high volume pumps use a bolt on cover that either has a second pickup to feed the pump from two places, or one larger pickup in the cover that replaces the factory design entirely. They are pricey, and as I said, you don't need it. You need good clearances, no taper on the journals, and careful assembly.
That being said, if you want to drill, the specialized bit I use is black oxide, high speed steel, and it's been used on a bunch of engines. Use oil, use the correct speed, and it's fine. Cast iron is very soft.
