340 intake/carburetor advice

Well, if you've already got a ThermoQuad that's ready to run and aren't going for every last bit of performance available and want good hood clearance, find a used Edelbrock regular 318-360 performer and port match it from the 273/318 size ports at the flanges to your 340/360 size gaskets. This is the probably going to be quickest and simplest way to do it on the cheap and the performance will be closer to the factory iron intake than an action plus. If you decide you need more out of it, mill the center divider to 1/2 inch from the upper level floor and install a one inch spread bore spacer. Being it sounds like the emphasis is more on cruising and enjoying it in a timely manner this would be the route I would take for now.