The lobes on the earlier distributor are different then the lobes on the later distributor, as is the dwell setting. So without actually seeing the condition of the lobes on the later distributor I would not want to venture a guess as to the condition, but generally, unless the lobes are pitted or rusty, or have been obviously damaged, they are likely fine. Usually, when I am rebuilding a 235 distributor, its the crud under the breaker plate, or rusted frozen advance weights, broken advance pins, or broken advance springs that are the culprit. I have an nos 2403 distributor that when I put it on my sun machine, the hardened grease prevented it from operating correctly. Had to give it a through cleaning before it worked properly, and that is NOS, so imagine what a 60 plus year old unit is like.
As the others have said, using the early steel distributor on the later motor's cast cam is probably not the right call here. So I agree, either swap gears or get the 2403 clean and squared away, or get a replacement 2403.
