Is it feasibly possible to take, for example, the latest Lionel SD40-2 or AC4400. Change the wheels, wire the unit to work correctly, fix both pilots, assuring the steps line up properly are correct in number of steps, and bend some wire. Some say there's some machining needed to be done. I've never done this but have looked a few time what it entails. I've 2railed Lionel non powered F7, that's not to back. Getting Atlas front pilot was the only challenge. Non powered units would be the most cost-effective solution for 2railing. I'm guessing a additional $200 to 2rail Lionel powered unit?
When I researched EMD and GEs history of units produced, most units were, of coarse GP7 &9s, F units, GP35s, U23s and some other units. In my opinion Atlas is a great product. It's to bad they have got so far behind in producing locomotives. SD40-2, GP38 and the latest GE generation of locomotives have the highest production orders from EMD & GE.
Maybe Atlas with the addition of MTH will go back and clean the MTH units up and offer them again with Atlas standards? Can only hope.
3rd Rail is a great option. But why offer the GE C44-9? The latter GE units have outsold the C44-9 by great numbers. ( I almost ordered 2 SP Tunnel motors last night. Still trying to rat hole $ for the F7s ordered from Atlas ) That last statement reflects I don't have lots of $ laying around for my passion of the hobby. Let along the time. Working on a layout is never ending. To add 2railing Lionel units would be another addition to the " to do " list. 3 WP & SP GP40-2s are my greatest need for my railroad. No one but Overland has produced those. In the end. It's a hobby. Greater challenges face us day to day. Stay happy everyone. Trust in our Lord Jesus Christ always.
John Corege