I don’t think it matters what it’s “for”, but I can tell you from my own swapping of transformers that the 16B-6 (MPU-200) will give you the most oomph in your flippers (all coils, for that matter). I was actually a doubter because I had built my QS with a 16B-3 (MPU-100) donor and figured it was purist nitpicking but I decided to swap in a 16B-6 from another game the extra power is noticeable.
My Galaxy might run on a 16B-3 now
Anyway, following your thread @mathazar, looking forward to seeing your progress!