Are you going to upgrade the exhaust? I like the early 70s 318 bbd, but unless you upgrade the exhaust, including opening the manifold outlet up to either 2 1/4 or 2 1/2 it's really all for naught.
Yes. it has an extremely restrive less than 2" exhaust out the back now, I am taking it to the muffler place and having a 2 1/2 all the way out installed the same week I swap out the motor.