I had a 1406 on my 355, in my opinion a good cruiser carb, not so good for top end performance. I had the strip kit and played with the jetting a fair amount and finally ended up buying a 650 Speed Demon pre Idle-Ez base plate.
The Demon and Barry Grant are two names I won't recommend. Though I have finally got the Speed Demon to work good enough without the assistance of the arrogant BG tech support team.
The keys to making it work for my motor were increasing the electric choke fast idle setting, bumping the accel pump discharge nozzle from .028 to .035 and running the green accel pump cam. 5.5 power valve, 68/76 mains, plain vac secondary spring. Due to the poorly engineered base plate the idle circuit still lacks the range of adjustability I would like but it does run decent and produces fuel milage similar to the 1406 and much better mid-high (3-6,500) RPM performance.
If I was going to replace it with one of the new carbs on the market I'd probably go Holley or Quick Fuel.
A lot depends on your driving style and your motor specs though. You're right on the fringe of a 750/770 cfm carb depending on the rpm you motor makes peak power.