Just thought I'd pass this along to those using O27 height wider radius track. Even these small differences can have one scratching their head when things just don't seem to line up. So you don't go nuts:
When using O54's, please note that the K-line version is 1/4 inch longer than Lionel's.
Correction: When using O42's , please note that the K-line version is 1/2 inch longer than Lionel's. Also K-line's O42 track has 5 ties, Lionel's have 3.