While the Williams units usually followed the Lionel tooling, not 100%, but close enough to think that the NW-2 shell could work on the Lionel engines that you mention Tom.
If not you may need to drill holes in the Lionel frame to match the mounting posts in the Williams shell. I did that with a Williams SD-45, turned the shell around so it would run the direction that I wanted the hood to be in. Find where you want the new hole to be and lightly mark it with a drill bit first before drilling the new hole.
Lee Fritz