66' 273 heads question

i ran a D4B on my 64 Barracuda wayyyyy back in 1970- 1973. It ran like a raped ape. I'm building another 273 now for a '65 /6 Barracuda and finally found another D4B for it. As soon as I fix all the little heli-coil problems I'll be ready to install it and hope to swap out the engines shortly after that.