Installing headers -- While engine pulled or after re-installed?
The easiest I think is to pull the drive shaft, shifter, clutch linkage and cross member. Pull the engine and tranny together. If you’re working by yourself it would be harder to get everything lined back up for the engine and transmission to go back together. Especially working on the ground, then it would be to just pull the whole thing. The headers aren’t to bad if you get the ones that fit the application. I put them in place in the engine well, the drivers side first if you have full length you have to pull a tierod and thread it through the headers. Then the passenger side when the engine is half way in.