I am considering putting together a multi-caliber Glock kit using a mid size frame (G19 size) as the basis. The goal is to have as many calibers available as possible. I am wondering which frame, 19, 23, 32, or 38 would be the best base for this kit. Are there significant frame differences that would limit calibers? I prefer to use a second generation frame or possibly one of the soon to be available G19 Timberwolf frames, as I like the fit better. What are your recommendations?