I would think that a Q-jet for a 305 would work just fine. You should be able to find a mid 70's vintage intake that will work along with the Q-jet. I believe that the 283 blocks have a hole in the rear of the block for a road draft tube. You may want to decide if you are going to use it to vent your engine or if you are going to update to a PCV valve system. Most 283's had the oil fill tube in the front of the intake manifold and used valve covers that had no holes in them. The later intake manifold doesn't have a provision for an oil fill tube. You have a few things to sort out, feel free to ask questions.
