Since you asked here is my two cents. If you are going to swap the motor anyway, I would not swap the heads and especially not the cam. Inviting trouble with the cam.
Electronic ignition might help if there is a problem with the points distributor. Not a bad idea to swap for long term since it will work with the new engine as well.
If you can find a cheap 4bbl intake to work with your 273 then do the swap 2bbl carb you have needs work.
Most of the changes you outlined sound like a lot of work and money for something that will only get stuck in the corner of the shop at some point and collect dust.
