Look up LKQ Auto Parts. Its a network of salvage yards all over the country. They also sell remanufactured long blocks with anywhere between 3/100k to 3/unlimited. I've bought and installed 12 of these engines in the last year and they have performed very well and the customers are happy. Especially with the unlimited mileage warranty. There is a national depot there in the DFW area. I have 1-830-303-5036 for the number to the one in Sequin, Tx. but they can give you the number for your local yard.
Also, Car-Part.com--Used Auto Parts Market search anywhere in the country for whatever you want. Any yard on the system shows their inventory, cost, address, phone and a lot of times, live chat.