I just got a Athearn S12 shell and frame and power trucks , Thank you Greg. I used to be able to deal with the hood width. I found scale drawings of both the VO 1000 and S12 and as far as I can tell the VO1000 has a 5' 69" wide hood and the S12 is 6' at least from the drawings . I was able to size the drawings so I could match the scale feet to my HO ruler so they lined up perfect, since the S12 drawing doesn't state the width yet both drawings do have a front view with a grid with a 0 on the center line out to 10' and I get 6' for an S12. I thought all the Baldwin switchers were the same hood width. If I get close to 5' 9" rather than 6' it will pass in my book. Even 6' will pass since the Athearn S12 is 7' wide.
I can remove the cab , slice the shell down the center and remove 1 scale foot then add with walk way's back to 10' the total width. I did this to make a VO 1000 years ago. I didn't remove the walk ways I just added styrene to bring them back to 10' across like the cab . I did remove the pilots because I needed them the proper width. I can do the same with this shell and I think to stock frame with a bit of narrowing where the frame fits in the shell leaving the area under the walk ways alone and the stock Athearn motor is 5 scale feet wide so it will fit. I see the frame where it fit the front is narrow enough it's just a bit wide near the cab and part of the front yet will still be strong enough. I can add some brass along the frames top if I need to stiffen it up some the trucks will clear . I could make the brass tall to add weight.
It's a lot of work yet I feel it can be done. I'd prefer an old Stewart S12 and there are some new ones out there yet I can't afford $100. If I recall Athearn later made a SW switcher maybe SW 1600 one had two stacks other had one and they were the scale EMD hood width on a different frame yet used the same power trucks different side frames.