OK, TBI stands for Throttle Body Injection. The cam is the shaft in the middle of the engine that opens the valves. A 350 cam is higher lift because it has to allow greater air/fuel mixture flow to the cylinders. However, the factory 305 cam from the 80s sucked. If the 350 cam is still good, change it into your 305. If your 305 is computerised, it should change the settings itself, to a point. You may have to swap the jets if they are to large. I hope thats it.