Any recommendations(brand,size) on an electric fan I am considering to help improve cooling on my recently rebuilt 340.How are these typically wired,.I noticed they draw over 20amps,should there be any concern of overloading the alternator.

Are you sure you need to add cooling capacity?
Is your new engine both broken in and well tuned?

If after this you still want to add an electric fan, you will need some relays and a knowledge of your under-hood electrics and wiring. There should be plenty of on-line sources for instructions in hooking one up.

I only used an electric fan in my 66 Charger, and it was wired so it only ran when the engine was running. This eliminated the electrical strain at start-up. Some people like to have it thermostatically controlled. I didn't.

So, answer the first two questions, then let's go from there.

I really wasn't sure if I needed to add cooling capacity.The engine is brand new ,well tuned and in the break-in period.(less than 20 miles).The temperature guage is part of my dashboard which is from a 69 Cuda,so I really didn't know the exact temperature I was running.Most of the time It was less than half pegged and when I was stopped in traffic for a while on an 80 degree day,It went past half almost to the next graduation on the guage.It ran at half the rest of the way home which was a 15 min.drive.When I got home I took a meat thermometor and put it in the top of the radiator and let the car idle for 20 min.At the half mark I was at 180 degrees and half way to the next mark which is the hottest it got it was at 185.I probably never exceeded 190 while I was driving.I'm just a little paranoid about overheating because I have put so much time into it.

This is what I did.Even after putting in a Griffin aluminum radiator I had problems when idling.I looked over the Spal catalog and found a very thin 16" pusher. I mounted that in front of the radiator behind the grill. I bought the wiring kit and mounted the relay under the battery tray. I wired an under dash mounted switch and I turn it on when I need to. I don't worry about accidentaly leaving it on because you can hear it.I tried it without the engine mounted fan and that didn't work well. Some folks recommend a HHR fan. My buddy just bought one for his Duster and couldn't make it fit. These are street cars not race cars and he didn't want to cut the car up. This has worked for me for 5 years.I was just in a parade for an hour idling and it held it below 200.

Sounds like a good alternative to supplement the cooling,rather than trying a new radiator.The radiator I have is from a 6cyl w/a/c ( 3 cores),and I had it reconditioned before I put it in.I was just looking at Griffin radiators,thinking I should bite the bullet and get one,but apparently that might not be the answer.I like what you did because you can control it when you need it and you still have your original fans.I am still in the break in period with the motor amd will keep an eye on it.
Thanks

Do it to save fuel and free up horsepower.

If you are looking to improve engine cooling, stock fan.