Jeff78rr - how big is your layout to handle 49 stack cars? Modifying the cars like you do is not in my wheelhouse - wow.
Regarding stack cars the following photos are comparisons of MTH RailKing, Lionel "027" size and MTH Premier. Being (re)new to the hobby I was shocked to see the extreme differences between cars. No LHS around to compare as I was starting back up.
Unfortunately I did not take measurements of any of these cars, sold them all off. I found the K-Line and Lionel "scale" cars play well together.
Following is a short video of my K-Line and Lionel intermodals running on my 9x13 layout.