Installing headers -- While engine pulled or after re-installed?

It is harder to leave the transmission in the car to pull the motor. With a 4 speed, you have the bell housing bolted to the block then the trans bolted to the bell with 4 bolts and the few for the cross member / mount. The input shaft on the trans is about 8 inches going though the throw out, clutch and then into the pilot. And the trans only have the rear mount to support it. The motor would have to go forward enough to clear the input shaft. On a lift the trans is out in about 20 minutes, in the ground / stands it’s about 30 minutes.

As for the headers, yeah the full leingth are tight going in, and it’s a dance of installing the headers as the motor is being lowered but it’s not aweful like headers in a 67 nova… once in there is plunty of space. A magnum starts is the “mini” and is necessary. Would also get a heat shield blanket to wrap the starter.