Do I need a computer with a 5.3L GEN III?

[echo72]

I'm going to purchase a 5.3L engine out of a 06 Silverado, but the computer (ECU) doesn't come with the motor. The motor has everything else like the throttle body, fuel injectors, harness, etc. I'm going to install this motor in a 72 Chevy Cheyenne pickup. Do I need to purchase a computer? If so, where do I get the computer and where do I get it programmed?

Thanks, Your help would be greatly appreciated.