Lou, K-Line never made a heavy Mikado. Just the USRA Light, which MTH had already done better. Lionel was the only one to tool up a proper USRA Heavy, and it has the backwards motor (because I presume it uses the same chassis as the K-Line Light.) That's the one I would like to upgrade.
The other Lionel Mikado isn't a USRA Light or Heavy. It's based on the Southern 4501 prototype. It's never been reissued with Legacy upgrades, and now that Lionel seems to have standardized on the ex-K-Line tooling, I doubt that it will be.