help decide on carb and master cyl for 318 charger

[BengalCharger]

Hello guys, i have recently started work on my 72 dodge charger that has not been started in the last 4-5 years, i have done the needful, changed the distributor and ecm as they were shot and she started and idles beautifully, the carb is old and has shaft play that causes a flat spot upon acceleration. i want to change the carb, should i replace it with what it has: a carter 2bbl or should i upgrade/change to a edelbrock or holley 600cfm 4 barrel unit? will i need to change the intake manifold? i saw many newer replacements available at the holley website but i am unaware of which one to go for keeping in mind decent economy and maybe better performance. my car is a 318 auto with 44000 miles since new.
also needed a brake master cylinder but there are several brands, which is a good one considering i cant always access parts being in dhaka, bangladesh.
my car is also 1/1 in the country i will also need a good online source for replacing suspension parts.
thanks in advance for the inputs
regards
asad