I would go with something in the 3000 range 9 or 10 inch converter. It will idle smoother in gear and drive better around town. You will also get a great response when you smash the loud pedal.

My car is mostly race car but I have driven it all over the country with an 8" 4500 and later a 4800 converter. I think even a stock 340 would benefit from a 3000 stall converter.