Lou,
Great idea. You are so creative!
Seriously, there are two basic ways to go here. One is a reproduction of a hard-to-find AC Gilbert Flyer set. The problem with that approach is Lionel has done so many Flyer Sets, Geeps and PAs over the last three decades that there would be resistance among collectors to buy more Gilbert inspired equipment unless it had not been made over and over again. For example, I bought the new Texas Special PAs because that is the first time Lionel has offered them with modern electronics and features; command control, RailSounds and fan driven smoke. I would not have ordered them otherwise.
The other approach is to use the newly tooled offerings with the electronics Lionel is packing into their S scale steam and diesels these days. Here, someone with your proven ability to create desirable trains could do wonderful thing for us hobbyists. How about a New Haven passenger set led by the electronically enhanced PAs for starters. Or you could use the new U-33 and SD-70ACe diesels to create a memorable freight set. Lionel has several newly tooled steamers that could be the basis for colorful freight or passenger sets. the possibilities are endless for someone with your fertile imagination, historical knowledge of O and S gauge trains and access to Lionel tooling.
Or you could really go crazy and convince Lionel to do the NYC Hudson with new scale tooling. Gee, it worked for the Vision Lionel Hudson. 
Just a few thoughts to get things rolling. Stay tuned, film at eleven
Ed Boyle
