For retrofit lifters with tie bars you dont need any machine work for normal sized cams. These are very expensive.
For useing oe rollers in older block its not a great way of doing things. I know it works but didnt think it was a good idea. I had both blocks setting next to each other did seems like it would work without a little risk. Oe is alot cheaper but only really good idea if the block alreay has the bosses and thinner walls cast. Drilling the main oil galley doesnt seem like a good idea.