Roger1,
As Steve points out there are different sizes of the Lionel Tin Plate, the 263E, then the mid size 264 and the smaller 262. I would not try to up grade the units, it's easier to find the exact engine you are looking for, and most times less expensive.
Labor today is a killer, even when some engines can be upgraded, unless you can do the work yourself and want to fully restore the complete engine.
PCRR/Dave