Welcome to the forum . . . . . certainly glad to have you aboard.
I could not find your linked models as still available from KenRayModels, however I did stumble on a list of (internet) dealers who have handled their models in the past.
Your querry, however, appears to relate to fitting some sort of a power mechanism to these Baldwin Sharknose 2000hp Passenger units. For a modification such as this you are going to need to acquire-at least the trucks from-ALCO PA units. Con-Cor, Life-Like, and Kato have offered these in the past. Perhaps-and I say only "perhaps"-the frames from these units could be stretched to fit under these KenRay body shells. These shells are longer than the PA shells and subsequently longer than it's framd and it might just be that the frame from an EMD passenger loke might would come out closer to the proper length.
A task such as this appears to be a daunting enterprise but the hobby press has covered techniques for stretching or shortening of body shells and/or frames on a number of occasions over the years. You can do a search of the master index to locate articles of this nature and then go to Railpub to locate the required issues. Don't get me wrong . . . . . I've never done this but back in the early '80s-about the time I began converting from Horribly Oversized-Scale to Noble-Scale-I was working in a hobby shop and in the display case there were a couple of the old Atlas FM C-liners-the B+A1A units-that I kept examining to see what it might take to render these to B+B units. I never tried it and I don't know of anyone who ever did but let me assure you that the same imagination that has captured you has captured others before you. Remember this, when you launch into an endeavor such as this it takes very meticulous work to keep from turning out a "Close but not cigar" final product.
And in a lot of locations they even release you on Sundays to spend with your family.
From the far, far reaches of the wild, wild west I am: rtpoteet
You might want to try and E8 drive. They are longer than the PA's and might be a better fit/ Both Kato and Life-Like made them. The Kato's the are better of the two.
Walthers has a listing for Bachmann in powered A-B sets but are listed as sold out. However, I first checked Bachmanns web site remembering them as the manufactorer, and they are not listed there.
Lengthened Alco PA. I believe ConCor offers or used to; a PA made by Kato.
so i was looking through some photos and i happened to come upon a picture of one of the prr's passenger sharks. so after some research, i happened to come upon shells such as these...
http://www.kenraymodels.com/images/lr003-ab.jpg
I was thinking about possibly kitbashing/modifying an existing model to fit these and i was looking for opinions, ideas, and possible locomotives to use.
NOTE: this is n scale