I'm sure it could be done, but is the cost worth it? average cost a few years ago for sleeves was $100 a hole...not sure if that's gone up or down in the past year or so, but if you figure that, plus the cost to machine the sleeves afterwards...you're probably looking at $1,000-$1200 to turn a 318 into a 340. how much would a 340 block run you at the swap meets, online, etc.?