theres a ton of vids on youtube about this,and also topics here in the forum.
basics,they sell a complete mopar swap kit on ebay for the distributor and electronics.
make Sure that you specify that you have a 400 Low Deck big block.
the 440 is a tall deck.
as for the carb,it depends if stock and how you use the car.
if its a cruiser/stock,then an Eddy carb would be perfect.
if its got some juice,ie,cam intake n all that,then a holley street demon or an older thermoquad would be my choice.
i will add to those by saying to make Sure that you have your kickdown for the transmission setup Correctly no matter which carb you install <> it is critical to your transmissions life.
some people will attempt to make a 2bbl linkage setup work,others will make their own linkage combos,and you can also buy Cable setups that are much nicer and easier than our factory linkage.