wrench 87 Not to step on anyones toes but, KCR would be the best bet for matching a carb to this motor. You are using his camshaft, and heads. You didn't say what rpm the motor is going to run in. THIS is a big thing. If the car is going to be a street car with a little track time, a dual plane manifold works great to about 5,500 rpms. This is where the single plane starts to take over and makes more power in the top end. Torque makes the car move, HP is what helps it go at high speed. You didn't print what the LSA is, so I am going with a 110. Which ever manifold you use, Sent it out to Joe craine and let him do a port matching job on it. He equalizes all the ports to flow within about 5-7 cfm. This helps balance out the rich and lean cylinders in the motor. Do you have an RPM limit on this motor? With a hydro roller camshaft about 6,500 is a good safe limit. I am not a big fan of big carbs. If this was my motor, a 650 dual feed dual pump with 50cc accellerator pumps would be just fine for around town driving and a little playing. A 780 would be the biggest I would use. I believe you are looking for drivability and MPG of better than 7-10. Either will need some dyno time to get the A/F numbers correct. If you live in a cooler weather climate, I wouldn't remove the choke housing for cold startups. It does effect the air flow into the motor and cost power. The other thing is your exhaust system, who's pipes are you going to run?
Back pressure is the biggest killer of cobra motors power. Running a real clean blow through system a 5-7 HP loss at top end, you do kill a little of the torque down bottom but this is a plus in most cases. It stops from blowing off the tires off idle. Some pipes cost about 20-30 hp in the upper rpm range. The trade off is noise and your hearing. Ear plugs are a plus either way in the left ear, unless you like that ringing sound after a drive. I have 2 sets of pipes, ones for the track and the orginials for the street. ERA makes both sets. Cops don't like the race pipes.
I am done Rick L.