I have a '67 coupe i was wonder if horns like the ones listed before would fit and if there would be alot of trouble installing them.

http://shop.ebay.com/i.html?_nkw=dixie+horn

 

You can't run the compressor via the stock horn wire. You'll have to setup a relay to switch the compressor. Here is a good site to get you up to speed on using relays: http://www.the12volt.com/relays/relays.asp

The next issue is where are you going to put all of those horns?