92 Sonoma engine swap

I have a 4.3l with a piston knock. Still has power and not bad mileage just embarassing idling. What I need to know is to install a vortec 4.3l do I have to change the computer, or can I get away with changing a chip? Is there other things need changing I'm not aware of? I'm hoping it's just replace. Thanks in advance for the info.