Are you certain that the fit is bad between the top and block? Most makers/restorers bevel the edges of the blocks a little so that the top can be removed more easily in the future. Though, I have to say that picture showed quite a gap.
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Famous last words: And with that- Im gone. You will probably read in the paper soon about a deranged kid who burns his bass in front of a luthier.
That's a gap larger than I usually see, but the above posters are correct about bevels. There is a great deal of surface area that is likely making perfect contact on that block. If you've ever tried to take a bass top off you will praise any maker who gave the block a slight bevel at the edges.
The block to be concerned with more in regards to gaps is the lower block as it typically has much less surface area contact (at least with the top).