[olddog]

That is a lot nicer car than the thread tittle and first post had me picturing.

Leave the 289 in it. Start by either replacing or rebuilding the existing carb. Sounds like you do not know much about carbs, so take it to a good tuner with a chassis dyno. You should be able to do this ~ $1000. Much less if you can do most of the work yourself. You will spend north of $3500 converting to EFI and you will still have to have it dyno tuned to get it right.

Once the engine is running in tip top shape, then decide if you want to swap out the auto for a manual. I would, but I wouldn't be in a big hurry.