It would appear that any of your changes caused the overheating, but you might want to consider "coincidence" and check some of the obvious things.
One easy thing to do is change your radiator cap back to the old
Take cap off and run car with heat on, making sure your coolant circulates inside the radiator (take a peek) and ensure you're getting heat
Hook up a vacuum gage on your manifold and observe the vacuum your getting (15+ and steady needle), making sure its not a head gasket (gage will show, - or maybe timing is way off). It all could cause overheating. Are you sure the radiator isn't plugged? Fan clutch working?
