Steamer is giving good advise, the 224E is a good engine and pulls quite well. If you can pick up a 763E at a reasonable price there is the prize. Just make sure it has a good E unit in it, before you purchase it.
Guns repaired & upgraded my Lionel 249 with ERR and man it's really something, pulls either 600 or 800 series rolling stock. It was Lionel's mid sized Tin Plate Engine and Tender. As far as I know I have the only 249 ERR around, Guns did a fantastic job on it.
If you like the MTH Repro Tin Plate with P2 or P3 there are a lots of good Tin Plate Engines and Train sets to pick from.
I do Caution about the 12 wheel Tenders on all these Tin Plate Trains, most Switches do not play well with them, some track does not either. IMO the very best switches for running them were the original Lionel 711's/072's & the original low voltage Super Snap K-Line Switches. The newer RMT SS are not exactly the same unfortunately, and most have problems of different types. Wish I would have never sold my original SS K-Line's, I still have my original Lionel 711's, I use LED's in them to keep the power draw to a minimum. We plan to set up a Conventional Tubular Layout just for my Tin Plate Consist's, with the 711/072 switches, as we continue building the new Train Room. I want the Conventional Tubular throw back look, for my Tin Plate Trains, along with my FasTrack, on some of the remainder of the Train Room layouts. Man how I wish Ross's Tin Plate Switches were really Tin Plate low voltage switches, we could really have used that modern engineering for our Tin Plate Trains.
Tin Plate Trains the Real Stuff! The 263E Work Train Consist on the over head self layout. My favorite O Gauge Train, nothing comes close, we own both the original Lionel and the MTH Repro P2 Work Trains, and the memories that goes with them.
Me with my Grandpa Christmas 1949-1950, running my Lionel 263E Work Train Christmas Present, given to me by my Father. It was his Christmas present as a young boy also. Little boys Lionel toys, handed down thru the generations in our family.