When doing a restoration project one is often faced with the decision to replace per the original design or make an improvement that corrects a flaw in the original design. Based on my experience with restoring vintage sports cars, the decision largely depends on the usage of the finished piece. If restoring for static display accuracy is very important. But when accuracy is this important it begs the question of why restore in the first place instead of preserving the object. If on the other hand the car (whether train or automobile) is to see regular service, improvements are likely appropriate. If the improvement is for safety or reliability it might be considered a necessity. And if the improvement is made in an unseen area there is little downside to incorporating the change.
The bottom line is before starting a restoration determine the intended purpose of the final item. Then do a lot of planning to ensure a sufficient knowledge base (and money) is available to meet the plan’s objectives. So what is the intended usage for 1006 and 1008 when restoration is complete?
Phil