Lionel actually included a closer drawbar mounting hole for their LC+ locos. No machining needed, simply disassemble the tender, remove the front truck, reseat the drawbar and reassemble.
The closer coupling works with O-48 and larger. I have not tested it on O-36, it would be tight and may not work at that diameter.
I have done this for my LC+ Hudson and Pacific. The Mikado is up next.
the first three photos are before modification, the last four are post-modification, and the middle are step-by-step photos of the easy process.