Do what you can with the intake manifold. Space is limited unless you get a sideways mount Cain 2-bbl becasue the EFI injector rail is very bulky and hits any stock position carb on an XD 1/2, or XE/XF intake. The XD 1/2 intake is very compact, but it isn't easy to sideways mount a 2-bbl carb ansd still get the air flow and power ypou need.
Cam wise, there are plenty of very specialised cams which can cater for your combination.
In New Zealand, the Ford Stock car guys are stuck with using a restrictor plate and only a 2-bbl carb. They have cams which build intake velocity by running a mini 'Nascar' cam profile. Kelford have made heaps of them to suit these econo racer engines. There is a nitrous or supercharger grinds, cheater cams, the whole nine yards
http://www.camshaftshop.com/camshafts/view/37/ford-6-cylinder-camshaft/
Best option is the wild street 155-E Fast street cam, rough idle, great midrange NZD$295.00 2500-5500rpm . It's a high intensity cam with lots and lots of 50 thou duration but not a lot of total duration. With a huge compression ratio, good detonation control you have massive effective compression great part throttle economy, and can run any of our more common 'little' 2-bbl carbs.
A couple of things.
The Holley 500 2300 series is not progressive.
The very rare 2305 350 and 500 Holley is.
There are a few 465 4160 series carbs which are 4-bbl vac sec or mechanical sec, and whatever Avenger and other carbs Holley makes these days. They are semi progessive carbs.
The 2300 500 Holley is cheap, effective, and can be tuned to suit. It runs clean and is very easy to be set up to be lean at part throttle, and rich at wide open throttle with the right power valve and jetting. It can yield 350 hp with the right cam and manifold on a 289.
The stock 34ADM is a bit too small, its only a 226 cfm at 1.5"Hg carb. The Essex 3000V6 used in Aussie Capris ran a brillant Weber 40 which can flow a lot of air, over 338 cfm at 1.5 "Hg. It can be bored out in the venturis to 35 mm, and looks very much like the ADM 34 to the passer by. It's the ultimate in stealth. Similer is the Weber DGAS 38...it is another good bolt on item which can be honed out to the 33 mm venturi size, can take the electric choke, and can flow a similar amout to the 500 cfm Holley (which is only a 354 cfm at 1.5"hg).
The Webers have a stock 46 by 93 mm bolt pattern, return line and can fit some of the aftermarket 14" air cleaners for the X-flow, along with the later electric choke.