So does my 340, and it's .060" for a bore of 4.1". I've seen plenty of Mopar small blocks go more than .030" without any issues at all. To say .030" is the "max" is just silly. I mean, I don't doubt that there are core shifted blocks out there that can only go .030" safely. Heck there may even be ones that won't go .030", there are some pretty badly core shifted examples running around. But .030" over as a max safe bore for all of them? Hogwash.
As for sleeves, perfectly fine, they work great. It's just an extra expense. If it's the original engine on a valuable car, it totally makes sense. If it's just some small block, find another one. The 340's aren't getting any easier to find though, so if you really want to keep the 340 it could be worth it. Some of the prices for 340 blocks I've seen lately would more than pay for sleeving all 8 holes in a block you already had.