Carb recommendations for my 340

Dan,
If you can find a TQ.......just run it. I could never work out why a 440 with a TQ [ #6410 ] had .125" sec jets but a #6454 used on a 360 had .143"sec jets.
Jet size is NOT related to engine size.

If you use a TQ on a 318, you may have to change jet sizes &/or met rods. What you will have is great throttle response, mileage & power.