carb choice and slick size

Many here have personal preference Holley or Carter (Edelbrock). Either one will do fine, the engine really doesn't care. Either carb, correctly calibrated will make the same power. Fuel+air go in, torque comes out. It's that simple. And to be honest, running 1/8 mile drags with 3.23 gears, it really won't matter.

The Edelbrock 1806 is pretty close to what Mopar installed on the 340 originally. You decide if that means anything. A Holley 670 Street Avenger would work well also. (1971 340's had a 750 CFM Thermoquad, with an "Air Valve Secondary")

I would keep the slick diameter as small as you reasonable can given your gears. Something in the 26x8 neighborhood. Slicks on a 14" rim?!?