I'm thinking about getting an 3.0L engine long block
 

I'm thinking about getting a 3.0 L engine long block FOR MY 1981 911SC. What do you recommend. Sticking with the Factory CIS or getting carburetor like a Weber or Zenith and if it's better to go with a carburetor with brand is better. I'm thinking about getting headers and want performance. Budget is currently up in the air. Also would like a nice quiet and gas efficient engine..
Thanks in advance

Your stated desires for the engine are in conflict with each other. First, I'm guessing you're in Brooklyn (NY). What does the state of New York say about smog for an '81? Do you intend to drive on the street? "A nice quiet and gas efficient engine" does not equal carbs in any shape or form. If NY allows, look into a programmable EFI system (there are plenty of threads here about this). It's been some time since I lived in NY, but I seem to remember that it gets COLD there; most header systems obviate cabin heat. Really, if you want carbs, PMO (1st choice) and Weber (2nd choice) are the only games in town. Good luck on the search/expedition/trek. You're just about to slip down a mountain from which you can't recover.

Thanks Don. I don't plan on driving the car during the winter mainly during the summers I just wasn't which way to go and wanted to know what was the main difference between the Weber type system compared to a stock CIS system

Aha! Fuel injection (in its various forms) will provide you with the best fuel economy and best all-around performance, although the programmable versions can waste gas as well as any carb system (if you desire). Carbs sing. Carbs spit, cough, gouge you in the eye. Cabs DO NOT like cold starts. When you install carbs with the correct cam shafts (ask 10 people here, you'll get 10 different recomendations), you'll be surprised. You'll lose your license on the LIE. . . Again, good luck!

stick with the CIS and spend your money on proper higher compression pistons and cylinders, SSI and sport exhaust you should get to 230-240hp

should I port and polish?
Thanks

Lot's of good info in Wayne's book about the modifications possible with an SC motor.