Do NOT let go of the block. Keep it. Find another 440 block for your car and have them build it. If you wouldn't of mentioned gear drives, aluminum heads and stuff, I would say 2 sleeves and go with it. But yer better off storing the original and just getting another short block. Save the original, you have a very rare expensive car. Depending on what area you live in, blocks are 100 to 400 bucks is all. Your numbers combo is worth much much more with it. Even if the engine is under a bench at home. Oh, if you can afford it right now, put the 2 sleeves in it. If your not racing, you could actually run it also. Sleeves will not cause a problem. What bore do they have to go anyways? If it needs 040 or bigger, you can sonic check it first. Some shops wont go over 20 or 30 for fear. I have run a 60 over with zero issues. Deepends on the casting thickness is all.