I've started this:
The conversion will be to a fantasy loco, a Santa Fe Pacific, in the style of 5001/3751/3460 classes, but one stage smaller: as if the "Santa Fe Big Three" were, instead, Four.
I am going to stretch the loco 1 1/4 inches overall, making it the same length as a scale Southern Crescent (a small Pacific, its about 3/4 inch shorter than the Alton Pacifics, etc.). I will add half an inch at the front of the boiler, half an inch at the rear of the boiler, and 1/4 inch in the longer, scale-sized cab. The boiler will be a scale 16 inches more diameter the the original LC+ steamer.
This is a more ambitious conversion than my previous four, in both the addition of so much length to the loco and in esthetics: I have no doubt I camn make a good looking loco body for it, but it will have a driver wheelbase quite short for its length, and that may make it look weird.
I removed the body of the steamer this time - the first time I did. I posted that separately with a title that should bring the posting up if people ever search for pictures inside an LC+ steamer. I was delighted that, unlike LC+ diesels, no wires and antenna, lights, etc., were attached to the inside of the body which would have complicated things.
I THOUGHT BRIEFLY about mounting another body entirely on it. I have the complete body from a Legacy ATSF Northern 3751 (long story, another time) and it fits over the chassis. But I could see no feasible way to trim it so short that it would look good. Down the road, I have some ideas for that approach - I think the Lionel scale small Pacific (Southern Crescent) would slip right on. But I don't have that body unless I remove if from my perfectly good Legacy loco, so . . . but I decided to go ahead and modify the existing LC+ body to be 'scale' and my new loco.
With the body off the loco, I could "very aggressively" take a saw to it (at least compared to how gently I did on the previous four conversions, and I did, as the photo below shows. I removd portions of the cab so that the bigger boiler will slip on back another 1/2 inch and other obstructions, etc. and made a new boiler shell out of polycarbonate tube to fit.
I know that I will move the stack forward between 1/4 to 1/2 inch. I do not know yet if I will do this by leaving the smoke unit where it is on the chassis and routing an S shaped pipe up and out the new, more forward stack (that will work if I only move the stack forward bu just 1/4 inch) or if I will relocate it first. I may do both. Note in the photo below, the smoke unit is held in place by two screws (red arrows point to the), 1/4 in apart. It appears that if I remove those screws, and move the unit forward a quarter inch (yellow arrow) I can screw the rearmost hole in the smoke unit's bracket to the forward most of the two holes in the chassis, moving the unit forward 1/4 inch. An S pipe would then take care of the other 1/4 inch I need. It appears that the wires will stretch that far and that the chassis will accomodate the relocation: in fact it looks like the whole thing has been made so that this could be done at the factory.
More as I get to it.