Best Carter 4 Barrel Carburetor for a stock 273?

To the OP
At the BEST of times, an engine such as yours with a 4bbl, might gain perhaps up to ~10%; so, on a 180hp engine, you might expect 18hp; but yur not gonna get it all, whatever that is, until the engine is wound up to the power-peak. The hp increase always begins, one hp atta time.
So, you know, maybe you get plus 1.1 hp at 2800 rpm, and gain an average of 1.1hp per 100 rpm to the Power-peak at say 4400rpm.
Since you have a basic 180 hp engine, even the smallest 4bbl out there will fill the bill. And since I have already successfully run the Big Thermoquad on several smog-era 318s, I see no reason why it couldn't be adapted to your 273. and so I say again, install whatever you got or can get for cheap, cuz it really doesn't matter. Myself, I would be partial to a small spread-bore.

Whereas, a 2800 convertor is gonna allow your engine rpm to jump from say 1800, to 2800, right at zero mph, and you can bet the farm that a 4bbl cannot touch the associated hp increase, of this 1000rpm jump.
But it doesn't stop there; as the rpm is gonna now be higher thru-out the rpm band, therefore, so will be the horsepower at any given mile-per-hour.
So, whereas the 4 bbl brings max power at say 4400, which might not be until 44mph with 2.76 gears, the
convertor brings it's max effect, right at zero-mph. Just
mash the pedal, watch the tach jump to where some power is, and send it!
I guarantee you that, the TC will put a bigger smile on your face than just about anything you can bolt on to a stock 273 with log manifolds, short of supercharging it.
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But you-know, I drive a standard transmission with a starter gear of 11/1, and can "stall" the engine at whatever rpm I want to;
so what do I know ...............
I live in Manitoba Canada, like around the 53rd parallel IIRC.. I drive my Barracuda from early-May to early-October. It used to be my DD.
The 367 in it,
has a 750 DP on an AirGap, with fresh cold air to the carb; and
the Idle-Timing is 12>14 degrees, and
since year 2000, she has never had a choke.
I get in, give her a couple of shots, twist the key, and just like that she comes alive. By the time she is backed out of the carport, and pointed in the "let's go" direction, she is in fact, almost, "ready to go". It takes 4>5 minutes to Idle past the school down the street, and then thru our dead little bedroom-town, before I get to the hiway, which will take me somewhere. By that time the heads are almost warm. A warm-up mile at 55/1900rpm, and it's wake-up time back in town, as the dual 3" cannons blast out the alarm-song.
and she does this on 87E10; which I highly recommend, cuz, you know, it has alcohol in it.......
which boils at 173*F;
which with 11/1 Scr/188psi CCP,
the heat of compression, has already made it ready to burn, long before the ignition system lights it off.
And that, friends, is why I threw my AFR gauge out, years ago.
You guys that insist on running conventional gas, IMO, are missing out on the 87alcohol, fast-burn, advantage.
>They say that we are gonna get 87E15 here shortly, which I will certainly try, perhaps even, embrace. I guess we'll see.