It can be done. The degree of relative reasonableness depends on the equipment available. The biggest challenge is to slice off most of the wood. Ideally, you'll find someone with a large, well-tuned bandsaw. After the block is cut to near its new size, the cut faces will need to be trued and cleaned up somewhat - this could be a job for a hand plane, a belt sander or a big (really big) disc sander. If you live in a region that has some foundries, then you might find a pattern shop with this sort of large-scale equipment.

In the absence of a large bandsaw, you could cut away most of the material in more difficult and/or messier ways, i.e. a chainsaw, or a deep circular saw cut all the way around followed by a lot of handsaw-work, etc. The messier the method of making the initial cut(s), the more cleanup work there will be at the end.

The most avalable saw big enough to resaw a chunk that size will be at a sawmill.

Seems to me that advertising is for sale ---eBay/Craigs List/etc. might be a better solution. A piece that size should be worth a fair amount of money.

Thanks for your suggestions.
Certainly Craig's list has been on my mind.
I doubt I'll get "a fair amount" of money but if it went to a loving home that might be a good enough reward.

I was asking because my counter needs a surface and it seems crazy to "buy" new wood, since I certainly couldn't buy anything as nice as what I have for "a fair amount" of money.

What part of the country do you live in?

Where are you going to find a bandsaw with a 30" high throat? Or, considering the smallest dimension, a 14" high throat? Depending on what a dovetailed butcher block is, you don't want to resaw it so as to weaken these joints and end up with an unstable wafer that will disintegrate into scraps.
If it has any value, it is the fashion in which the separate strips of wood were assembled into this huge block. If you diminish the block, you're losing value rather than gaining. Maple is not an unreasonably expensive wood, better to sell the block and buy new lumber, IMO.
Casey

txmat or others who might be interested. The block has toured the U.S. over the years but currently resides in Manhattan. By definition not enough room.

Casey: Where are you going to find a bandsaw with a 30" high throat? Or, considering the smallest dimension, a 14" high throat?

The last shop I worked in (a large foundry pattern shop in Ohio)had several saws big enough to handle the 14" dimension. Mostly these were 36" Oliver and Tannewitz models, with throats up to 24" high. We also had a 36" disc sander. Sadly, I'm doubtful there would be much such machinery in Manhattan. The biggest problem the OP would face, I think, would be transporting the block to someone who could work on it; the resizing could go quite quickly.

Jon,
I thought a 30" bandsaw would do it, but you either have one or you don't. They're hard to rent/borrow. Next question is, how are you going to lift that bad boy up to the table? You'd have to verify with a metal detector that it contains no bolts. I take it that's what the dovetails take the place of, though.
Then they could use that wide-belt thickness sander to flatten the new slabs, assuming they didn't fall apart.
Casey

Oh c'mon, it's only -- what -- 400 pounds or so? Haven't you eaten your spinach?