I was just in the GMC Sierra section of the forums for my father's truck, and this guy got a 305 from a '90 Caprice and is gonna use it to replace the 350 in his '90 truck. What do you guys think? Its got the torque, but horsepower might be an issue right? Isnt this sort of a downgrade??

yeah it is a downgrade for sure, but with a few mods it would not be that bad

It Really Would Be...try Puttin An Intake..headers And A High Performance Ignition And Youll Be N Bizness