The drill bits are almost three feet long.
If you find a Buick 'guy' you might rent them, or I would see what he would charge to do it. You don't have to worry about going too deep. Its more about keeping it true/straight. I did mine free hand, and fv@ked it up (*there is a GN/GS guy here I know pretty well, let me use them in his shop). I just managed to salvage the block by soldering it up! If a machine shop charged you $50 its still worth it. Then they will vat the block, add new cam bearings and freeze plugs, but, you should pick up
Grand National cam bearings ($15 or so) buy two sets (v8's need one more bearing). Might call around, the cam bearing part number was like B12-B. Also score a rubber rear main seal, seems like it was from a Ford 300 straight six. Use the turbo v6 or just later model, like the 4.1 front timing cover seal too. The 350's have rope front and rear main seals, bah! its junk!!!