I have a 440 and it wont stop over heating ive replaced every thing but it still over heats. I did have the raditor powder coated can this have any affect on my overheating?  

powder on radiator will restrict air flow, paint on mopar radiator fins was a very light black 15 degree black flat i believe? try swapping out thermostat to a colder running temp model, thermostat has temp listed on it, small print, find what it says and get one that is 10-15 degrees cooler. is it your guage saying its hot or actually boiling over? guage could be wrong more likely than not if thats your main thought tht is reading high? you can put a candy thermometer in a pan of boiling water and your old thermostat and when it reaches the proper temp while boiling the thermostat should open, if not its defective. just some thoughts to help. you have any recommendations on who can rebuild master cylinders, alternators, distributors etc?  

I will asume the vehicle did not over heat before you powder coated the rad. If so, you have already answered your own question.
Yes powder coating a rad can cause a vehicle to overheat.
You will most likely need to replace the rad with one large enough to cool your big engine. Your thermostat will also need replacing since it to has seen an excessive amount of heat and will likely be contributing to the problem.
Hopefully the engine has no damage such as a blowen head gaskets, cracked head etc.  

Get an aluminum radiator from jegs, or have that one recored. Re cored will cost at least $200. A cooler t-stat will not always help. See what the OE t-stat temp is. Most later 440's was 195. If you put in a 160 it may stay open and not close to cool the water in the radiator.