Hmmmm. The wheels in my head are spinning again

I have two 360 blocks that need the lifter gallery’s tubed. Now I have no issues doing this on a stock 360 block but both of these have already been machined. Bad things can happen as we all know when enlarging a hole 10 inched in a stock cast iron block. Messing up a 50.00 block wouldn’t kill me but 1000.00 block would. Well while looking for my long 5/8 drill bit for the soft 1/2 (5/8 outside dia) house water line I usually use I grabbed a piece of my K&S tubing I keep handy. Wow is this a nice fit. A fast ream with my 9/16 drill bit and tap it in. Only issue I see is it is only .014 thick. I have the Direct Connection peening tool so I’m not worried about tearing it. What do you guys think about this. I’m thinking I’m going to give it a go.