A 4160 carb is its style..Whats the CFM of the carb? For a 302 that spins 6000 rpms you dont even need a 500cfm carb so if your carb is bigger than 500cfm's it maybe running way too lean......
Im almost certain Ford intake manifolds have a 4150 flange and an adapter to convert to 4160 isnt gonna work as it causes airleaks so Im feeling your problem ATM is the carb flange style..
Was the carb specifically ordered for your application?
Calculator tools let you know what size is adequate for your application but style of carb is dictated by the type of intake being used
Your idle with an auto is 700-750 and with a manual around 800-850 or what is stated by the aftermarket camshaft manufacturer if one is installed,,
Without knowing more about the carb it sounds like there could be a multitude of possible issues...
Do you have the right intake with 4160 style intake flange also correct intake gasket and are you using carb studs to hold the carb down and not using bolts that may be too long?
Do you have a vacuum gauge?...Its the best tool when you have a carb because you get the best vacuum with the best tuning.......
The more I drive with the new carburetor, the carburetor idle seems more where I think it ought to be, around 750-800 RPM once the temp gauge hits the half way mark.