You could do either one first.
I like to install the rod first. While I'm in there, I can look around, check out what's happening in there, and use new, high quality gaskets to seal it back up. That way, I can leave the governor and stock carb on it, tweak the springs on the governor, change the exhaust, air filter and flywheel as I acquire parts.
Start with a good, safe foundation.
Have fun and be safe.