Maybe the carb, distributor, and the fuel pump. The Olds and Chevy motors are more different than alike. I haven't seen your other post, so I'm not sure what motor you are pulling out.
In my opinion, you have two possible approaches. If you have the 307 Olds (Y or 9 code), the easier swap is to an Olds 350, since it would be a direct bolt in. If you have a 305 Chevy (H code) the Chevy 350 would be an easier swap.
To answer your question however, the two engines are very different in accessory locations, brackets, and motor mounts. I don't know if anything will swap easily. I know there is a sticky regarding swapping a Chevy V8 into 3.8 V6 car. This will provide a ton of info.