To another gentleman that mentioned not much room for the 327 in the 55 Chevy, believe it or not, the block was physically about the same size as the 265 CID that the Chevy came with originally.
Yep same size, but there was plenty of room under the hood, putting in a 427 was a popular mod just had to modify the firewall. The Tim Taylor method was to bash the firewall back with a sledge hammer. There were kits that moved the radiator foward instead, in fact I think there was a 426 Hemi kit.