Welcome to the world of hotrodding!
I would go with a new conversion kit, less headaches in my opinion. By the time you try to "salvage yard" the conversion for a '65, you will have spent nearly as much in time and gas than you would getting the new kit. I also would try to hook up with a local speed shop to make the buy, might be a few dollars more, but they are local and can't hide behind a website.
Good luck!