Vince
It sounds like you are at the next stage of the train hobby: Build & Bash......
Fortunately/Unfortunately we do get to the stage where we want a "long out of production or a Never Was" train of piece of rollingstock.
And the ONLY was we're going to get it, is to build or bash...
There are lots of donor/inexpensive pieces of rolling stock to test your build/bash skills upon to get what you want.
IF YOU BUILD IT, YOU'LL HAVE IT....
Happy Rails...
dave