Sorry to bust your bubble young man, but the 366 is pretty much worthless as a performance motor. It is a big block motor, but is the smallest of the big blocks. The tiny bore (3.935") cannot be bored far enough to yield any appreciable cubic inches. The stock stroke is 3.760", same as the 396 and 427, but both those motors use a larger bore. You could install a stroker crank for more cubic inches, but the cost of the crank and special pistons would be prohibitive compared to the power you could get from other motor combinations.
To answer your question about the deck, that's the flat part of the block where the heads bolt on. The tall deck block is (I believe) 0.400" taller than a standard block like a 396, 427 and 454.
There were some tall deck 427 and 454 blocks that can be used effectively to make a large displacement motor, but your 366 block isn't one of them. Sorry.