440 source Stealth Heads or Trick Flow 270

With 512 cubic inches and a 4-1/4 inch crank, you are knocking on the back door of what used to be original B-1 head territory. In fact, modern cylinder head even has a street ported version of B1 originals for engines in the 496 to low 500 inch range. 270 TFS is an excellent head and would be my choice. What kind of block do you have to withstand all the power this build is going to make? The research I have done shows this is a build for a 400 (preferably cold weather) block with BCR caps and girdle as a minimum starting point with preference being a cross bolted main block...