If you want a quick and dirty solution to getting your 258 running great contact Gronk about the ECM test bypass, coil upgrade, and the motocraft 2150 swap...
In the process you can eliminate much of the vacuum spaghetti from the engine compartment, and the end result is an easily tuneable carb, so you don't have to battle the ancient emissions gear to get it running.
That being said, I don't have solid advice regarding the outcome of emissions tests, I'm not sure if you can easily pass after the swap, because I don't live in an area that requires it so I've never tried.
I mucked about with the carter carb for a bit, got really frustrated, then got a holly replacement that was still computer controlled before finally abandoning ship and opting for the "n u t t e r b y p a s s" and essentially eliminating all but the ignition module from the equation.
Shhhhh, I didn't say that.