When changing a 305 Chevy pick up engine with a carburetor to a 350 Chevy block that had electronic ignition?

This is a relative simple swap as they are both the same basic engine. As far as the serpentine belts you can buy pulleys to update at Jegs or any major auto supply. I don't know why you don't want the electronic ignition, they are more dependable and accurate. Take the fuel pump and rod out of the 86 and pull the plate off the 90 and install.