well, I like the Pennsy, I'd like to see a streamlined K4 Pacific, this should be easy since you already have the mechanism all you would need would be the shell, preferably die cast metal with your usual superb paint job, Mikado (not USRA) old PFM brass ones used to be a dime a dozen, but not any more, and Bowser has discontinued their kits so these are things of the past too and H series Consies, these would cover a lot of models because there were over 1000 of them on the PRR and several series (H7, H8, H9, H10 etc) several years ago Sunset ran these in brass with interchangeable tenders, smokebox fronts and other parts, allowing the modeler to mix and match, as the PRR did with the real ones, these were used throughout the system right up until the end of steam both as road engines and heavy switchers (the Pennsy only had 2, I think, 0-8-0s) so any Pennsy layout can use a hand full