The amount of misinformation on this board about carb sizing is staggering. Any performance carb will supply "enough gas" to mix with the air that can flow through the carb. The 500 cfm carb will support about 300 horsepower. That's using the rule of thumb of 0.6 hp per cfm.

Thousands of 413s ran millions of hours with two-barrel carburetors, pumping water and performing other industrial tasks. As I have said in a previous post my family car in the early '70s was a 2-barrel 455 olds which would run 90 in the quarter and would top out over 100 mph, the fastest indicated speed I ever saw was about 122 but the stock speedometer could have been lying too. (Growing up in North Dakota had its advantages in that there was hardly ever a cop around on the roads I drove.) The carb on that car was the larger Rochester two-barrel which I doubt flowed more than 375 cfm rated as a two-barrel carb, which would be about 265 rated as a 4-barrel.
Keep in mind also the thousands of dirt track racers using the Holley 4412 500 cfm 2-barrel, which would be 353 cfm rated as a 4-barrel.

Stick on a 500 instead of a 750 and you are leaving about 100 top end hp on the table. This power loss should all be above the torque peak. The car will run really strong until it "runs out of breath" which will be a disappointment but will not be accompanied by any expensive noises. Try it and see what you think. You can always buy a bigger carburetor later.

R.