I found the seat for the float needle valve loose in the base of carb causing the car to flood out at low rpm and run rich at other speeds. I don't see anything that would hold the seat in the base other than a press fit. Now the seat just drops in the bore with a loose slip fit. The carb was recently rebuilt before I got the car according to maintenance records. The needle top also appears to be filed off. Looks like someone really butchered these parts. Any info on how the seat is supposed to be secured will be appreciated.

It was common for those seats to come loose. They were only a press fit. There was an oversize made but I'm not sure it ever made it to the parts file. I always fixed them with my own technique. That was to lay the seat in the gap formed by an almost closed vise. With a sharp punch and a sharp impact form a series of around 10 dimples in the area of interference. This is similar to knurling and expands the overall diameter. Drive the seat back into the carb bowl and get a new needle.